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Lu, Huayi e6fa411af0 DWS DEV 830.201 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2024-05-16 07:24:04 +00:00

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<a name="EN-US_TOPIC_0000001188588994"></a><a name="EN-US_TOPIC_0000001188588994"></a>
<h1 class="topictitle1">ALTER TABLE</h1>
<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000001188588994__s51e2da63c58c4d33aec745544ede4792"><h4 class="sectiontitle">Function</h4><p id="EN-US_TOPIC_0000001188588994__p17187172419520"><strong id="EN-US_TOPIC_0000001188588994__b660619531562">ALTER TABLE</strong> is used to modify tables, including modifying table definitions, renaming tables, renaming specified columns in tables, renaming table constraints, setting table schemas,<span id="EN-US_TOPIC_0000001188588994__ph148383532819"> enabling or disabling row-level access control,</span> and adding or updating multiple columns.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001188588994__s5aa34d2c05d246c2a34d4d04d18241d8"><h4 class="sectiontitle">Precautions</h4><ul id="EN-US_TOPIC_0000001188588994__u915ee5ff73574f6a87b62430e86088f9"><li id="EN-US_TOPIC_0000001188588994__lb90bf107d7124d74bb54d17159878dc4">Only the owner of a table, a user granted with the ALTER permission for the table, or a system administrator has the permission to run the <strong id="EN-US_TOPIC_0000001188588994__b57351314162518">ALTER TABLE</strong> statement. To change the owner or schema of a table, you must be the owner of the table or a system administrator.</li><li id="EN-US_TOPIC_0000001188588994__l5ee8c1f921db4b3e971b52ce381f3fb4">The storage parameter <strong id="EN-US_TOPIC_0000001188588994__b842352706111223">ORIENTATION</strong> cannot be modified.</li><li id="EN-US_TOPIC_0000001188588994__lf500fa19f5a148098b231f30fff48b02">Currently, <strong id="EN-US_TOPIC_0000001188588994__b842352706111547">SET SCHEMA</strong> can only set schemas to user schemas. It cannot set a schema to a system internal schema.</li><li id="EN-US_TOPIC_0000001188588994__l35ba23f08a6a45fca0f3e1d89036cf92">Column-store tables support <strong id="EN-US_TOPIC_0000001188588994__b429212453159">PARTIAL CLUSTER KEY</strong> but do not support table-level foreign key constraints. In 8.1.1 or later, column-store tables support the <strong id="EN-US_TOPIC_0000001188588994__b106487311918">PRIMARY KEY</strong> constraint and table-level <strong id="EN-US_TOPIC_0000001188588994__b265519184198">UNIQUE</strong> constraint.</li><li id="EN-US_TOPIC_0000001188588994__l2044ad89d52a4fa19c204625a523e8e6">In a column-store table, you can perform <strong id="EN-US_TOPIC_0000001188588994__b842352706111730">ADD COLUMN</strong>, <strong id="EN-US_TOPIC_0000001188588994__b842352706111736">ALTER TYPE</strong>, <strong id="EN-US_TOPIC_0000001188588994__b842352706111742">SET STATISTICS</strong>, <strong id="EN-US_TOPIC_0000001188588994__b1805286499115611">DROP COLUMN</strong> operations. The types of new and modified columns should be the <a href="dws_06_0008.html">Data Types</a> supported by column storage. The <strong id="EN-US_TOPIC_0000001188588994__b842352706111758">USING</strong> option of <strong id="EN-US_TOPIC_0000001188588994__b84235270611183">ALTER TYPE</strong> only supports constant expression and expression involved in the column.</li><li id="EN-US_TOPIC_0000001188588994__le58702930a1543c594eb7d08d7ccff5f">Only the <strong id="EN-US_TOPIC_0000001188588994__b20441183617396">NULL</strong>, <strong id="EN-US_TOPIC_0000001188588994__b25684123915">NOT NULL</strong>, and <strong id="EN-US_TOPIC_0000001188588994__b0472143203916">DEFAULT </strong>constant values can be used as HDFS table column constraints.Only the <strong id="EN-US_TOPIC_0000001188588994__b9511147143914">DEFAULT </strong>value can be modified (<strong id="EN-US_TOPIC_0000001188588994__b361175613391">SET DEFAULT</strong> and <strong id="EN-US_TOPIC_0000001188588994__b1963990144011">DROP DEFAULT</strong>), and only the <strong id="EN-US_TOPIC_0000001188588994__b522612416402">NOT NULL</strong> constraint can be deleted. Currently, <strong id="EN-US_TOPIC_0000001188588994__b20891693407">NULL</strong> and <strong id="EN-US_TOPIC_0000001188588994__b17981101254016">NOT NULL</strong> constraints cannot be modified.</li><li id="EN-US_TOPIC_0000001188588994__li153471115174112">When you modify the COLVERSION or <strong id="EN-US_TOPIC_0000001188588994__b981472410207">enable_delta</strong> parameter of a column-store table, other ALTER operations cannot be performed.</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001188588994__u020939a35b814d88bd79ebaa89184c70"><li id="EN-US_TOPIC_0000001188588994__lda486815fe2c48219181818e1c160730">Auto-increment columns cannot be added, or a column in which the <strong id="EN-US_TOPIC_0000001188588994__b1428872417175239">DEFAULT</strong> value contains the nextval() expression cannot be added either.</li><li id="EN-US_TOPIC_0000001188588994__li186651927183319">Row-level access control cannot be enabled for HDFS tables, foreign tables, and temporary tables.</li><li id="EN-US_TOPIC_0000001188588994__li0583173815413">If you delete the PRIMARY KEY constraint by specifying the constraint name, the NOT NULL constraint is not deleted. You can manually delete the NOT NULL constraint as needed.</li><li id="EN-US_TOPIC_0000001188588994__li148501915101119">The <strong id="EN-US_TOPIC_0000001188588994__b1342573082819">cold_tablespace</strong> and <strong id="EN-US_TOPIC_0000001188588994__b166502325286">storage_policy</strong> parameters of <strong id="EN-US_TOPIC_0000001188588994__b7748164114286">ALTER RESET</strong> cannot be used in OBS multi-temperature tables, and <strong id="EN-US_TOPIC_0000001188588994__b1365218116296">COLVERSION</strong> cannot be changed to <strong id="EN-US_TOPIC_0000001188588994__b10715722911">1.0</strong> for such tables.</li><li id="EN-US_TOPIC_0000001188588994__li1797485513153">You can change a column-store table whose <strong id="EN-US_TOPIC_0000001188588994__b1174917308354">COLVERSION</strong> parameter is <strong id="EN-US_TOPIC_0000001188588994__b1309139193518">2.0</strong> to an OBS multi-temperature table. The <strong id="EN-US_TOPIC_0000001188588994__b395112381373">COLD_TABLESPACE</strong> and <strong id="EN-US_TOPIC_0000001188588994__b183338419374">STORAGE_POLICY</strong> parameters must be added.</li><li id="EN-US_TOPIC_0000001188588994__li16531226131810">You can use <strong id="EN-US_TOPIC_0000001188588994__b17747141512553">ALTER TABLE</strong> to change the values of <strong id="EN-US_TOPIC_0000001188588994__b11822172595516">STORAGE_POLICY</strong> for <strong id="EN-US_TOPIC_0000001188588994__b10687164418557">RELOPTIONS</strong>. After the cold/hot switchover policy is changed, the cold/hot attribute of the existing cold data will not change. The new policy takes effect for the next cold/hot switchover.</li><li id="EN-US_TOPIC_0000001188588994__li1246245516214">When an <strong id="EN-US_TOPIC_0000001188588994__b1053230163720">ALTER TABLE</strong> operation is performed on a table, it triggers table rebuilding. During this rebuilding process, data is dumped into a new data file. Once the rebuilding is complete, the original file is deleted. However, it is important to note that if the table is large, the rebuilding process can consume a significant amount of disk space. When the disk space is insufficient, exercise caution when performing the <strong id="EN-US_TOPIC_0000001188588994__b18740634113719">ALTER TABLE</strong> operation on large tables to prevent the cluster from being read-only.<ul id="EN-US_TOPIC_0000001188588994__ul1438822935513"><li id="EN-US_TOPIC_0000001188588994__li17721142710548">Change the data type of a column.</li><li id="EN-US_TOPIC_0000001188588994__li1845735210572">Add columns (including the oid column) to a row-store table.</li><li id="EN-US_TOPIC_0000001188588994__li111869119114">Modify <strong id="EN-US_TOPIC_0000001188588994__b1968463713378">COLVERSION</strong> for a column-store table.</li><li id="EN-US_TOPIC_0000001188588994__li182521207316">Specify the DEFAULT constant values for a column added to a column-store table, while the DEFAULT values contain volatile functions or the DEFAULT values are not NULL and do not belong to a specific data type.</li></ul>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001188588994__s9a54be85a5fc4e58bbd51d452fe9c1be"><h4 class="sectiontitle">Syntax</h4><ul id="EN-US_TOPIC_0000001188588994__u12bf63c1411a4772ac68f8c282118026"><li id="EN-US_TOPIC_0000001188588994__l302162fed8634729943dbe2cd4a1c831"><strong id="EN-US_TOPIC_0000001188588994__b84235270613584">ALTER TABLE</strong> modifies the definition of a table.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s9e7e0d247038441296df71bd20dd2fcb"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">[</span><span class="o">*</span><span class="p">]</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="n">action</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">];</span>
</pre></div></td></tr></table></div>
</div>
<div class="p" id="EN-US_TOPIC_0000001188588994__aa57bdf51649a420caca25a91c38a1fd1">There are several clauses of <strong id="EN-US_TOPIC_0000001188588994__b84235270611209">action</strong>:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s6946877e56a04391bb00725ca674eeeb"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span>
<span class="normal">19</span>
<span class="normal">20</span>
<span class="normal">21</span>
<span class="normal">22</span>
<span class="normal">23</span>
<span class="normal">24</span>
<span class="normal">25</span></pre></div></td><td class="code"><div><pre><span></span><span class="n">column_clause</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="n">table_constraint</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">VALID</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="n">table_constraint_using_index</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">VALIDATE</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">RESTRICT</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">CASCADE</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">CLUSTER</span><span class="w"> </span><span class="k">ON</span><span class="w"> </span><span class="n">index_name</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">WITHOUT</span><span class="w"> </span><span class="k">CLUSTER</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="n">storage_parameter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value</span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">RESET</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">storage_parameter</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">OWNER</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">new_owner</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="n">TABLESPACE</span><span class="w"> </span><span class="n">new_tablespace</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="err">{</span><span class="n">COMPRESS</span><span class="o">|</span><span class="n">NOCOMPRESS</span><span class="err">}</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">REPLICATION</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">ROUNDROBIN</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[,...]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">GROUP</span><span class="w"> </span><span class="n">groupname</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">NODE</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">nodename</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="n">NODE</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">nodename</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DELETE</span><span class="w"> </span><span class="n">NODE</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">nodename</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">DISABLE</span><span class="w"> </span><span class="k">TRIGGER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">trigger_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">USER</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="k">TRIGGER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">trigger_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">USER</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="n">REPLICA</span><span class="w"> </span><span class="k">TRIGGER</span><span class="w"> </span><span class="k">trigger_name</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="n">ALWAYS</span><span class="w"> </span><span class="k">TRIGGER</span><span class="w"> </span><span class="k">trigger_name</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">DISABLE</span><span class="w"> </span><span class="k">ROW</span><span class="w"> </span><span class="k">LEVEL</span><span class="w"> </span><span class="k">SECURITY</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="k">ROW</span><span class="w"> </span><span class="k">LEVEL</span><span class="w"> </span><span class="k">SECURITY</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">FORCE</span><span class="w"> </span><span class="k">ROW</span><span class="w"> </span><span class="k">LEVEL</span><span class="w"> </span><span class="k">SECURITY</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">NO</span><span class="w"> </span><span class="k">FORCE</span><span class="w"> </span><span class="k">ROW</span><span class="w"> </span><span class="k">LEVEL</span><span class="w"> </span><span class="k">SECURITY</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">REFRESH</span><span class="w"> </span><span class="k">STORAGE</span>
</pre></div></td></tr></table></div>
</div>
<div class="note" id="EN-US_TOPIC_0000001188588994__note72241047509"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul1262412162508"><li id="EN-US_TOPIC_0000001188588994__l6ca789b5332d4287955cbc3b4f033bd4"><strong id="EN-US_TOPIC_0000001188588994__a678b1bf3bc0144889dd38038a553c636">ADD table_constraint [ NOT VALID ]</strong><p id="EN-US_TOPIC_0000001188588994__ad1344efa2bdc49a58d03500a6cc0c7e9">Adds a new table constraint.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l31205d866e444a6dbe6f25f75fd7ac0a"><strong id="EN-US_TOPIC_0000001188588994__adc92225dd4114a45b78377a2bf4c7a3c">ADD table_constraint_using_index</strong><p id="EN-US_TOPIC_0000001188588994__aa863bd159eef4beaa99c62e75b53fc67">Adds primary key constraint or unique constraint based on the unique index.</p>
</li><li id="EN-US_TOPIC_0000001188588994__lef0a0526d0064f50b18c8558f5662514"><strong id="EN-US_TOPIC_0000001188588994__a472dae3c54024503970467de6d9e5ce7">VALIDATE CONSTRAINT constraint_name</strong><p id="EN-US_TOPIC_0000001188588994__a732e241994554884b888d149f7e01b51">Validates a foreign key or check constraint that was previously created as <strong id="EN-US_TOPIC_0000001188588994__b84235270615248">NOT VALID</strong>, by scanning the table to ensure there are no rows for which the constraint is not satisfied. Nothing happens if the constraint is already marked valid.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l3d175ff7e4c44fbb959e2bd2e6adf14c"><strong id="EN-US_TOPIC_0000001188588994__a4fec4135a7e546b3b37de29d6d5c9e86">DROP CONSTRAINT [ IF EXISTS ] constraint_name [ RESTRICT | CASCADE ]</strong><p id="EN-US_TOPIC_0000001188588994__a9ea3ce9933234a68819d72211de7387f">Drops a table constraint.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l81d42dcac163498ea75bbf805aed41d2"><strong id="EN-US_TOPIC_0000001188588994__a3cee97513ffe46e5ab0f213d9094be47">CLUSTER ON index_name</strong><p id="EN-US_TOPIC_0000001188588994__aaf1b1cdd8d574ef0bf5572de7916c4fb">Selects the default index for future <strong id="EN-US_TOPIC_0000001188588994__b154057964144250">CLUSTER</strong> operations. It does not actually re-cluster the table. </p>
</li><li id="EN-US_TOPIC_0000001188588994__l789a9ccbf7db454a887c42f666dc62de"><strong id="EN-US_TOPIC_0000001188588994__a624b880fc5f34d738e1949ae5a7ed38c">SET WITHOUT CLUSTER</strong><p id="EN-US_TOPIC_0000001188588994__abd9c5f7eac49424db45b55c2b10a72d2">Removes the most recently used <strong id="EN-US_TOPIC_0000001188588994__b1503816654144218">CLUSTER</strong> index specification from the table. This operation affects future cluster operations that do not specify an index.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li56571130135116"><strong id="EN-US_TOPIC_0000001188588994__a7ce06e107cdd4ade9e87dd3867da1fe6">SET ( {storage_parameter = value} [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__p185710613613">Changes one or more storage parameters for the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l65bd7be27d6349b38b9fddef863ab652"><strong id="EN-US_TOPIC_0000001188588994__aee0fd04c17834369918b9838fdb5402b">RESET ( storage_parameter [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__a8fd98d74215843dfa6e538db58d6e179">Resets one or more storage parameters to their defaults. As with <strong id="EN-US_TOPIC_0000001188588994__b87802723394049">SET</strong>, a table rewrite might be needed to update the table entirely.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l3b052855374a4343be1422ada947293d"><strong id="EN-US_TOPIC_0000001188588994__a2c5d62e75cd24bca9570ec354e00b110">OWNER TO new_owner</strong><p id="EN-US_TOPIC_0000001188588994__aa0e47b15efc748b09e69cba274fe3ed3">Changes the owner of the table, sequence, or view to the specified user.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l67980d2e0b574e369e92db42e3cc8f90"><strong id="EN-US_TOPIC_0000001188588994__acc8441d6a41e4d5d88292ef41c77670f">SET {COMPRESS|NOCOMPRESS}</strong><p id="EN-US_TOPIC_0000001188588994__a4a18f2079bdd460c9206217b7e18430d">Sets the compression feature of a table. The table compression feature affects only the storage mode of data inserted in a batch subsequently and does not affect storage of existing data. Setting the table compression feature will result in the fact that there are both compressed and uncompressed data in the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li12789455592"><strong id="EN-US_TOPIC_0000001188588994__b19540553195910">DISTRIBUTE BY { REPLICATION | ROUNDROBIN | { HASH ( column_name [,...] ) } }</strong><p id="EN-US_TOPIC_0000001188588994__p202554124011">Changing a table's distribution mode will physically redistribute the table data based on the new distribution mode. After the distribution mode is changed, you are advised to manually run the <strong id="EN-US_TOPIC_0000001188588994__b194161389134">ANALYZE</strong> statement to collect new statistics about the table.</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note17151727415"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul207632714384"><li id="EN-US_TOPIC_0000001188588994__li87639773820">This operation is a major change operation, involving table distribution information modification and physical data redistribution. During the modification, services are blocked. After the modification, the original execution plan of services will change. Perform this operation according to the standard change process.</li><li id="EN-US_TOPIC_0000001188588994__li4764879389">This operation is a resource-intensive operation. If you need to modify the distribution mode of large tables, perform the operation when the computing and storage resources are sufficient. Ensure that the remaining space of the entire cluster and the tablespace where the original table is located is sufficient to store a table that has the same size as the original table and is distributed in the new distribution mode.</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__lc0248f93a46e4f93988c52a1689d03c5"><strong id="EN-US_TOPIC_0000001188588994__a1842fc66567242f98cc850430911fba7">TO { GROUP groupname | NODE ( nodename [, ... ] ) }</strong><p id="EN-US_TOPIC_0000001188588994__ab2cd51efb3474c34a488f0795ff376ff">The syntax is only available in extended mode (when GUC parameter <strong id="EN-US_TOPIC_0000001188588994__b842352706171750">support_extended_features</strong> is <strong id="EN-US_TOPIC_0000001188588994__b842352706171755">on</strong>). Exercise caution when enabling the mode. It is used for tools like internal dilatation tools. Common users should not use the mode.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li56519590587"><strong id="EN-US_TOPIC_0000001188588994__b1965105945817">ADD NODE ( nodename [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__p3651115913587">It is only available for tools like internal dilatation. General users should not use the mode.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1657714219591"><strong id="EN-US_TOPIC_0000001188588994__b757772185916">DELETE NODE ( nodename [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__p7577228597">It is only available for internal scale-in tools. Common users should not use the syntax.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li96011923154115"><strong id="EN-US_TOPIC_0000001188588994__b4856193213527">DISABLE TRIGGER [ trigger_name | ALL | USER ]</strong><p id="EN-US_TOPIC_0000001188588994__p1756911432476">Disables a single trigger specified by <strong id="EN-US_TOPIC_0000001188588994__b18279133716429">trigger_name</strong>, disables all triggers, or disables only user triggers (excluding internally generated constraint triggers, for example, deferrable unique constraint triggers and exclusion constraints triggers).</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note952219464525"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001188588994__p852274613524">Exercise caution when using this function because data integrity cannot be ensured as expected if the triggers are not executed.</p>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__li20336415185413"><strong id="EN-US_TOPIC_0000001188588994__b1792831616553">ENABLE TRIGGER [ trigger_name | ALL | USER ]</strong><p id="EN-US_TOPIC_0000001188588994__p1055911685411">Enables a single trigger specified by <strong id="EN-US_TOPIC_0000001188588994__b1438171810528">trigger_name</strong>, enables all triggers, or enables only user triggers.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li4405143218417"><strong id="EN-US_TOPIC_0000001188588994__b10572162711555">ENABLE REPLICA TRIGGER trigger_name</strong><p id="EN-US_TOPIC_0000001188588994__p1598142917322">Determines that the trigger firing mechanism is affected by the configuration variable <strong id="EN-US_TOPIC_0000001188588994__b8265174916207">session_replication_role</strong>. When the replication role is <strong id="EN-US_TOPIC_0000001188588994__b7359124025416">origin</strong> (default value) or <strong id="EN-US_TOPIC_0000001188588994__b027916429542">local</strong>, a simple trigger is fired.</p>
<p id="EN-US_TOPIC_0000001188588994__p4569943164716">When <strong id="EN-US_TOPIC_0000001188588994__b25803248554">ENABLE REPLICA</strong> is configured for a trigger, it is fired only when the session is in <strong id="EN-US_TOPIC_0000001188588994__b436324219556">replica</strong> mode.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li7530636164112"><strong id="EN-US_TOPIC_0000001188588994__b16269436205518">ENABLE ALWAYS TRIGGER trigger_name</strong><p id="EN-US_TOPIC_0000001188588994__p1323484582310">Determines that all triggers are fired regardless of the current replication mode.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1024418116410"><strong id="EN-US_TOPIC_0000001188588994__b1244911642">DISABLE/ENABLE ROW LEVEL SECURITY</strong><p id="EN-US_TOPIC_0000001188588994__p57428381684">Enables or disables row-level access control for a table.</p>
<p id="EN-US_TOPIC_0000001188588994__p6244611943">If row-level access control is enabled for a data table but no row-level access control policy is defined, the row-level access to the data table is not affected. If row-level access control for a table is disabled, the row-level access to the table is not affected even if a row-level access control policy has been defined. For details, see <a href="dws_06_0169.html">CREATE ROW LEVEL SECURITY POLICY</a>.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1473416210320"><strong id="EN-US_TOPIC_0000001188588994__b18584175214519">NO FORCE/FORCE ROW LEVEL SECURITY</strong><p id="EN-US_TOPIC_0000001188588994__p59117412819">Forcibly enables or disables row-level access control for a table.</p>
<p id="EN-US_TOPIC_0000001188588994__p3735826322">By default, the table owner is not affected by the row-level access control feature. However, if row-level access control is forcibly enabled, the table owner (excluding system administrators) will be affected. System administrators are not affected by any row-level access control policies.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li19266104642419"><strong id="EN-US_TOPIC_0000001188588994__b35891614125211">REFRESH STORAGE</strong><p id="EN-US_TOPIC_0000001188588994__p16674133892712">Changes the local hot partitions that meet the criteria specified in the <strong id="EN-US_TOPIC_0000001188588994__b87096016427">storage_policy</strong> parameter of an OBS multi-temperature table to the cold partitions stored in the OBS.</p>
<p id="EN-US_TOPIC_0000001188588994__p1514015952817">For example, if <strong id="EN-US_TOPIC_0000001188588994__b1091113494315">storage_policy</strong> is set to <strong id="EN-US_TOPIC_0000001188588994__b9677103717436">'LMT:10'</strong> for an OBS multi-temperature table when it is created, the partitions that are not updated within the last 10 days are switched to cold partitions in the OBS.</p>
</li></ul>
</div></div>
</div>
<ul id="EN-US_TOPIC_0000001188588994__u49a5c5d45c844b069a2387398ac5d1a8"><li id="EN-US_TOPIC_0000001188588994__lc7cb80d336ec4f28a7cae883a3553c86">There are several clauses of <strong id="EN-US_TOPIC_0000001188588994__b842352706112426">column_clause</strong>:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s314d493dc2f4449f885f9a11c5ff703a"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span>
<span class="normal">19</span>
<span class="normal">20</span>
<span class="normal">21</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ADD</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">compress_mode</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLLATE</span><span class="w"> </span><span class="k">collation</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">column_constraint</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">]</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="n">data_type</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">default_expr</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="n">comment_text</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">RESTRICT</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">CASCADE</span><span class="w"> </span><span class="p">]</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DATA</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">TYPE</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLLATE</span><span class="w"> </span><span class="k">collation</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="p">]</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="err">}</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">STATISTICS</span><span class="w"> </span><span class="p">[</span><span class="n">PERCENT</span><span class="p">]</span><span class="w"> </span><span class="nb">integer</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">STATISTICS</span><span class="w"> </span><span class="p">((</span><span class="w"> </span><span class="n">column_1_name</span><span class="p">,</span><span class="w"> </span><span class="n">column_2_name</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">))</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">index_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLLATE</span><span class="w"> </span><span class="k">collation</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">opclass</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">ASC</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DESC</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">NULLS</span><span class="w"> </span><span class="k">LAST</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="k">method</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="s1">'text'</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">LOCAL</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">PARTITION</span><span class="w"> </span><span class="n">index_partition_name</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">storage_parameter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">index_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">(</span><span class="err">{</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLLATE</span><span class="w"> </span><span class="k">collation</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">opclass</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">ASC</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DESC</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">NULLS</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">FIRST</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">LAST</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">}</span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="k">method</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="s1">'text'</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="n">storage_parameter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value</span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">WHERE</span><span class="w"> </span><span class="n">predicate</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="n">index_name</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">CHANGE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="n">old_column_name</span><span class="w"> </span><span class="n">new_column_name</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">default_expr</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="s1">'text'</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DELETE</span><span class="w"> </span><span class="k">STATISTICS</span><span class="w"> </span><span class="p">((</span><span class="w"> </span><span class="n">column_1_name</span><span class="p">,</span><span class="w"> </span><span class="n">column_2_name</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">))</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="n">attribute_option</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value</span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">RESET</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">attribute_option</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span>
<span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">STORAGE</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">PLAIN</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">EXTERNAL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">EXTENDED</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">MAIN</span><span class="w"> </span><span class="err">}</span>
</pre></div></td></tr></table></div>
</div>
<div class="p" id="EN-US_TOPIC_0000001188588994__p144115326344"><div class="note" id="EN-US_TOPIC_0000001188588994__note1915883013419"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul1013725218345"><li id="EN-US_TOPIC_0000001188588994__li17319125313343"><strong id="EN-US_TOPIC_0000001188588994__b19575316173418">ADD [ COLUMN ] column_name data_type [ compress_mode ] [ COLLATE collation ] [ column_constraint [ ... ] ]</strong><p id="EN-US_TOPIC_0000001188588994__p1576316153419">Adds a column to a table. If a column is added with <strong id="EN-US_TOPIC_0000001188588994__b102431218124919">ADD COLUMN</strong>, all existing rows in the table are initialized with the column's default value (<strong id="EN-US_TOPIC_0000001188588994__b32441918194914">NULL</strong> if no <strong id="EN-US_TOPIC_0000001188588994__b624513189493">DEFAULT</strong> clause is specified).</p>
</li><li id="EN-US_TOPIC_0000001188588994__li205811116193410"><strong id="EN-US_TOPIC_0000001188588994__b165841416133418">ADD ( { column_name data_type [ compress_mode ] } [, ...] )</strong><p id="EN-US_TOPIC_0000001188588994__p1858631603412">Adds columns in the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1024214213357"><strong id="EN-US_TOPIC_0000001188588994__b258919161342">MODIFY [ COLUMN ] column_name data_type</strong><p id="EN-US_TOPIC_0000001188588994__p162482021153511">Modifies the data type of an existing field in a table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li12846527155913"><strong id="EN-US_TOPIC_0000001188588994__b17326017141519">MODIFY [ COLUMN ] column_name [ CONSTRAINT constraint_name ] NOT NULL [ ENABLE ]</strong><p id="EN-US_TOPIC_0000001188588994__p148461627125915">Adds a NOT NULL constraint to a column of a table. Currently, this clause is unavailable to column-store tables.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li19652534929"><strong id="EN-US_TOPIC_0000001188588994__b3549132631514">MODIFY [ COLUMN ] column_name [ CONSTRAINT constraint_name ] NULL</strong><p id="EN-US_TOPIC_0000001188588994__p76521534422">Deletes the NOT NULL constraint to a certain column in the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li46251910104619"><strong id="EN-US_TOPIC_0000001188588994__b13153326134710">MODIFY [ COLUMN ] column_name DEFAULT default_expr</strong><p id="EN-US_TOPIC_0000001188588994__p1231910589478">Changes the default value of the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li3352528134716"><strong id="EN-US_TOPIC_0000001188588994__b7629155404715">MODIFY [ COLUMN ] column_name COMMENT comment_text</strong><p id="EN-US_TOPIC_0000001188588994__p17570156491">Modifies the comment of the table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li353213421351"><strong id="EN-US_TOPIC_0000001188588994__b553464263516">DROP [ COLUMN ] [ IF EXISTS ] column_name [ RESTRICT | CASCADE ]</strong><p id="EN-US_TOPIC_0000001188588994__p15535154293511">Drops a column from a table. Index and constraint related to the column are automatically dropped. If an object not belonging to the table depends on the column, <strong id="EN-US_TOPIC_0000001188588994__b761688268153314">CASCADE</strong> must be specified, such as foreign key reference and view.</p>
<p id="EN-US_TOPIC_0000001188588994__p1253712429359">The <strong id="EN-US_TOPIC_0000001188588994__b2027582094049">DROP COLUMN</strong> form does not physically remove the column, but simply makes it invisible to SQL operations. Subsequent insert and update operations in the table will store a <strong id="EN-US_TOPIC_0000001188588994__b1963218215329">NULL</strong> value for the column. Therefore, column deletion takes a short period of time but does not immediately release the table space on the disks, because the space occupied by the deleted column is not reclaimed. The space will be reclaimed when <strong id="EN-US_TOPIC_0000001188588994__b182313719311">VACUUM</strong> is executed.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1538511245367"><strong id="EN-US_TOPIC_0000001188588994__b12389112483618">ALTER [ COLUMN ] column_name [ SET DATA ] TYPE data_type [ COLLATE collation ] [ USING expression ]</strong><p id="EN-US_TOPIC_0000001188588994__p143921924193617">Change the data type of a field in the table. Only the type conversion of the same category (between values, character strings, and time) is allowed. Indexes and simple table constraints on the column will automatically use the new data type by reparsing the originally supplied expression.</p>
<p id="EN-US_TOPIC_0000001188588994__p4397724173619"><strong id="EN-US_TOPIC_0000001188588994__b16268158134915">ALTER TYPE</strong> requires an entire table be rewritten. This is an advantage sometimes, because it frees up unnecessary space from a table. For example, to reclaim the space occupied by a deleted column, the fastest method is to use the command.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen103991424113620"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="n">anycol</span><span class="w"> </span><span class="k">TYPE</span><span class="w"> </span><span class="n">anytype</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p11406202419368">In this command, <strong id="EN-US_TOPIC_0000001188588994__b17674153722016">anycol</strong> indicates any column existing in the table and <strong id="EN-US_TOPIC_0000001188588994__b142595427203">anytype</strong> indicates the type of the prototype of the column. <strong id="EN-US_TOPIC_0000001188588994__b81109238504">ALTER TYPE</strong> does not change the table except that the table is forcibly rewritten. In this way, the data that is no longer used is deleted.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li125215194714"><strong id="EN-US_TOPIC_0000001188588994__b6255145119478">ALTER [ COLUMN ] column_name { SET DEFAULT expression | DROP DEFAULT }</strong><p id="EN-US_TOPIC_0000001188588994__p5257951174712">Sets or removes the default value for a column. The default values only apply to subsequent <strong id="EN-US_TOPIC_0000001188588994__b165154918894049">INSERT</strong> commands; they do not cause rows already in the table to change. Defaults can also be created for views, in which case they are inserted into <strong id="EN-US_TOPIC_0000001188588994__b60099307165618">INSERT</strong> statements on the view before the view's <strong id="EN-US_TOPIC_0000001188588994__b4022857165618">ON INSERT</strong> rule is applied.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li16393616422"><strong id="EN-US_TOPIC_0000001188588994__b194213615424">ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL</strong><p id="EN-US_TOPIC_0000001188588994__p1944106134217">Changes whether a column is marked to allow <strong id="EN-US_TOPIC_0000001188588994__b9856123923214">NULL</strong> values or to reject <strong id="EN-US_TOPIC_0000001188588994__b1290814419322">NULL</strong> values. You can only use <strong id="EN-US_TOPIC_0000001188588994__b1945912820323">SET NOT NULL</strong> when the column contains no <strong id="EN-US_TOPIC_0000001188588994__b184641611331">NULL</strong> values.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1068251364212"><strong id="EN-US_TOPIC_0000001188588994__b14682131394216">ALTER [ COLUMN ] column_name SET STATISTICS [PERCENT] integer</strong><p id="EN-US_TOPIC_0000001188588994__p10682181317425">Specifies the per-column statistics-gathering target for subsequent <strong id="EN-US_TOPIC_0000001188588994__b433222536101758">ANALYZE</strong> operations. The value ranges from <strong id="EN-US_TOPIC_0000001188588994__b19314158185">0</strong> to <strong id="EN-US_TOPIC_0000001188588994__b134121501816">10000</strong>. Set it to <strong id="EN-US_TOPIC_0000001188588994__b1173265614504">-1</strong> to revert to using the default system statistics target.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1493571614422"><strong id="EN-US_TOPIC_0000001188588994__b1793591619423">{ADD | DELETE} STATISTICS ((column_1_name, column_2_name [, ...]))</strong><p id="EN-US_TOPIC_0000001188588994__p59351216124213">Adds or deletes the declaration of collecting multi-column statistics to collect multi-column statistics as needed when <strong id="EN-US_TOPIC_0000001188588994__b1880183203516">ANALYZE</strong> is performed for a table or a database. The statistics about a maximum of 32 columns can be collected at a time. You are not allowed to add or delete the declaration for system tables or foreign tables</p>
</li><li id="EN-US_TOPIC_0000001188588994__li04101364333"><strong id="EN-US_TOPIC_0000001188588994__b16410736103317">ADD { INDEX | UNIQUE [ INDEX ] } [ index_name ] ( { { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [ ASC | DESC ] [ NULLS LAST ] } [, ...] ) [ USING method ] [ COMMENT 'text' ] LOCAL [ ( { PARTITION index_partition_name } [, ...] ) ] [ WITH ( { storage_parameter = value } [, ...] ) ]</strong><p id="EN-US_TOPIC_0000001188588994__p3410536173318">Create an index for the partitioned table. For details about the parameters, see <a href="dws_06_0165.html">CREATE INDEX</a>.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li16283110183411"><strong id="EN-US_TOPIC_0000001188588994__b14284101347">ADD { INDEX | UNIQUE [ INDEX ] } [ index_name ] ({ { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ] }[, ...] ) [ USING method ] [ COMMENT 'text' ] [ WITH ( {storage_parameter = value} [, ... ] ) ] [ WHERE predicate ]</strong><p id="EN-US_TOPIC_0000001188588994__p14284110123416">Create an index on the table. For details about the parameters, see <a href="dws_06_0165.html">CREATE INDEX</a>.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li14581184353511"><strong id="EN-US_TOPIC_0000001188588994__b185814435356">DROP { INDEX | KEY } index_name</strong><p id="EN-US_TOPIC_0000001188588994__p45811443183520">Deletes an index from a table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li19581164319353"><strong id="EN-US_TOPIC_0000001188588994__b165814432355">CHANGE [ COLUMN ] old_column_name new_column_name data_type [ [ CONSTRAINT constraint_name ] NOT NULL [ ENABLE ] |</strong><p id="EN-US_TOPIC_0000001188588994__p1458114319354"><strong id="EN-US_TOPIC_0000001188588994__b358234353510">[ CONSTRAINT constraint_name ] NULL | DEFAULT default_expr | COMMENT 'text' ]</strong></p>
<p id="EN-US_TOPIC_0000001188588994__p105822439354">Modifies the column information in the table, such as column names and column field information.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li18868131914427"><strong id="EN-US_TOPIC_0000001188588994__b38682197428">ALTER [ COLUMN ] column_name SET ( {attribute_option = value} [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__p11868201984212"><strong id="EN-US_TOPIC_0000001188588994__b178681719194215">ALTER [ COLUMN ] column_name RESET ( attribute_option [, ... ] )</strong></p>
<p id="EN-US_TOPIC_0000001188588994__p178681819134218">Sets or resets per-attribute options.</p>
<p id="EN-US_TOPIC_0000001188588994__p4844910182318">The attribute option parameters are <strong id="EN-US_TOPIC_0000001188588994__b1963034012540">n_distinct</strong>, <strong id="EN-US_TOPIC_0000001188588994__b3462354165410">n_distinct_inherited</strong>, and <strong id="EN-US_TOPIC_0000001188588994__b493019594548">cstore_cu_sample_ratio</strong>. <strong id="EN-US_TOPIC_0000001188588994__b1218813515573">n_distinct</strong> specifies and fixes the statistics of a table's distinct values. <strong id="EN-US_TOPIC_0000001188588994__b159271377581">n_distinct_inherited</strong> specifies and inherits the distinct value statistics. <strong id="EN-US_TOPIC_0000001188588994__b428811561131">cstore_cu_sample_ratio</strong> specifies the CU ratio for <strong id="EN-US_TOPIC_0000001188588994__b107781648842">ANALYZE</strong> on a column-store table. Currently, the <strong id="EN-US_TOPIC_0000001188588994__b341355110816">n_distinct_inherited</strong> parameter cannot be <strong id="EN-US_TOPIC_0000001188588994__b16966111010919">SET</strong> or <strong id="EN-US_TOPIC_0000001188588994__b571911201393">RESET</strong>.</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note1477151114114"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul10775274419"><li id="EN-US_TOPIC_0000001188588994__li187759715414">n_distinct<p id="EN-US_TOPIC_0000001188588994__p117751974411"><a name="EN-US_TOPIC_0000001188588994__li187759715414"></a><a name="li187759715414"></a>Sets the distinct value statistics of the column.</p>
<p id="EN-US_TOPIC_0000001188588994__p18775157144118">Value range: -1.0 to INT_MAX</p>
<p id="EN-US_TOPIC_0000001188588994__p107761572419">Default value: <strong id="EN-US_TOPIC_0000001188588994__b123833312209">0</strong>, indicating that this parameter is not set.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li2776117174119">n_distinct_inherited<p id="EN-US_TOPIC_0000001188588994__p17762744116"><a name="EN-US_TOPIC_0000001188588994__li2776117174119"></a><a name="li2776117174119"></a>Sets the distinct value statistics of the column in an inherited table.</p>
<p id="EN-US_TOPIC_0000001188588994__p127769710415">Value range: -1.0 to INT_MAX</p>
<p id="EN-US_TOPIC_0000001188588994__p1377619719417">Default value: <strong id="EN-US_TOPIC_0000001188588994__b159013509216">0</strong>, indicating that this parameter is not set.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li877657104114">cstore_cu_sample_ratio<p id="EN-US_TOPIC_0000001188588994__p1977613784115"><a name="EN-US_TOPIC_0000001188588994__li877657104114"></a><a name="li877657104114"></a>Specifies the expansion multiple in the calculation of CUs to be sampled during ANALYZE on a column-store table.</p>
<p id="EN-US_TOPIC_0000001188588994__p877619784119">Value range: 1.0-10000.0</p>
<p id="EN-US_TOPIC_0000001188588994__p1577617713419">Default value: <strong id="EN-US_TOPIC_0000001188588994__b138329229">1.0</strong></p>
</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__li27101623104210"><strong id="EN-US_TOPIC_0000001188588994__b107091223174217">ALTER [ COLUMN ] column_name SET STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN }</strong><p id="EN-US_TOPIC_0000001188588994__p97102023154211">Sets the storage mode for a column. This clause specifies whether this column is held inline or in a secondary TOAST table, and whether the data should be compressed. This statement can only be used for row-based tables. SET STORAGE only sets the strategy to be used for future table operations.</p>
</li></ul>
</div></div>
</div>
<ul id="EN-US_TOPIC_0000001188588994__u8cca88f0413844bea856b7c300dfd7d5"><li id="EN-US_TOPIC_0000001188588994__l92eab49fc61a4659aaef996d3df3ec99"><strong id="EN-US_TOPIC_0000001188588994__b9811164913719">column_constraint</strong> is as follows:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s582355bc707640e59b1c74747b8411c3"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span>
<span class="normal">7</span>
<span class="normal">8</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">CHECK</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">default_expr</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="n">index_parameters</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="n">index_parameters</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">DEFERRED</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">IMMEDIATE</span><span class="w"> </span><span class="p">]</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__l77267d65eedc4c45b5c4815b352c99fd"><strong id="EN-US_TOPIC_0000001188588994__b842352706171324">compress_mode</strong> of a column is as follows:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s83119060825743d8b58505ee50a28c77"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">[</span><span class="w"> </span><span class="n">DELTA</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">PREFIX</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DICTIONARY</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">NUMSTR</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">NOCOMPRESS</span><span class="w"> </span><span class="p">]</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</li></ul>
<ul id="EN-US_TOPIC_0000001188588994__uefc5a74112ad49b2a69642abd7856395"><li id="EN-US_TOPIC_0000001188588994__ld1bc704c86df461a893736267b491884"><strong id="EN-US_TOPIC_0000001188588994__b842352706112756">table_constraint_using_index</strong> used to add the primary key constraint or unique constraint based on the unique index is as follows:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__se5bce9c9760342bca32b711c2bd90686"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">index_name</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">DEFERRED</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">IMMEDIATE</span><span class="w"> </span><span class="p">]</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<ul id="EN-US_TOPIC_0000001188588994__u12a8254fba024ba88e8de81a493bbcd0"><li id="EN-US_TOPIC_0000001188588994__lfab3772088214fe8a954e1271fa21fb9"><strong id="EN-US_TOPIC_0000001188588994__b84235270610618">table_constraint</strong> is as follows:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__sf2a998bd853e4633a62a25c59f44d327"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">CHECK</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="n">expression</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="n">index_parameters</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="n">index_parameters</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">DEFERRED</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">INITIALLY</span><span class="w"> </span><span class="k">IMMEDIATE</span><span class="w"> </span><span class="p">]</span>
</pre></div></td></tr></table></div>
</div>
<div class="p" id="EN-US_TOPIC_0000001188588994__a11bb2f032ea1407abd3bbd9e668d02aa"><strong id="EN-US_TOPIC_0000001188588994__b8423527069548">index_parameters</strong> is as follows:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s8c487a90cde6479f8515dc152b551b7d"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="p">[</span><span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="n">storage_parameter</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">value</span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">TABLESPACE</span><span class="w"> </span><span class="n">tablespace_name</span><span class="w"> </span><span class="p">]</span>
</pre></div></td></tr></table></div>
</div>
</div>
</li></ul>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001188588994__u64cb039dde3a4b86bd07e1b828045ea1"><li id="EN-US_TOPIC_0000001188588994__li143652117270">Changes the data type of an existing column in the table. Only the type conversion of the same category (between values, strings, and time) is allowed.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1943194813271"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">table_name</span>
<span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="o">|</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="n">default_expr</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="s1">'text'</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__l21ee0985b0704017aa42e670e7d894a5">Rename the table. The renaming does not affect stored data. The new table name cannot be prefixed with the schema name of the original table.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s3aaad1216fc24dd9915c12cf36819135"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span>
<span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">new_table_name</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__l967c45a3216a4ffb977ed4c71ca709fe">Rename the specified column in the table.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s73c886bdc33a44798e243190a885344e"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">[</span><span class="o">*</span><span class="p">]</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">)</span><span class="err">}</span>
<span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">new_column_name</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__lea6876479fc44a66a80a97382a76d933">Rename the constraint of the table.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__sb40d2ff5960a4a7481e957449f4627f9"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">[</span><span class="o">*</span><span class="p">]</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">ONLY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="err">}</span>
<span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">new_constraint_name</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__l548edbe35555410fa24b4b1f0f6d23c1">Set the schema of the table.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s735d1054fcbb4380a94d12e31754f532"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span>
<span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">new_schema</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<div class="note" id="EN-US_TOPIC_0000001188588994__note4645185715577"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul12482610135811"><li id="EN-US_TOPIC_0000001188588994__li174822107589">The schema setting moves the table into another schema. Associated indexes and constraints owned by table columns are migrated as well. Currently, the schema for sequences cannot be changed. If the table has sequences, delete the sequences, and create them again or delete the ownership between the table and sequences. In this way, the table schema can be changed.</li><li id="EN-US_TOPIC_0000001188588994__li116251735815">To change the schema of a table, you must also have CREATE privilege on the new schema. To add the table as a new child of a parent table, you must own the parent table as well. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE permission on the table's schema. These restrictions enforce that altering the owner does not do anything you could not do by dropping and recreating the table. However, a system administrator can alter ownership of any table anyway.</li><li id="EN-US_TOPIC_0000001188588994__lc89e9156b1a24f54ab4b56cb62425a1f">All the actions except for <strong id="EN-US_TOPIC_0000001188588994__b128403402994049">RENAME</strong> and <strong id="EN-US_TOPIC_0000001188588994__b69167430294049">SET SCHEMA</strong> can be combined into a list of multiple alterations to apply in parallel. For example, it is possible to add several columns or alter the type of several columns in a single command. This is useful with large tables, since only one pass over the table need be made.</li><li id="EN-US_TOPIC_0000001188588994__l52482ac4319140b39e980212bc4e1b87">Adding a <strong id="EN-US_TOPIC_0000001188588994__b117459547694049">CHECK</strong> or <strong id="EN-US_TOPIC_0000001188588994__b63163342094049">NOT NULL</strong> constraint requires scanning the table to verify that existing rows meet the constraint.</li><li id="EN-US_TOPIC_0000001188588994__l3a477688715a4b2faf6ccd00edeebdc3">Adding a column with a non-null default or changing the type of an existing column will require the entire table to be rewritten. Table rebuilding may take a significant amount of time for a large table; and will temporarily require as much as double the disk space.</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__leb45f314816c43899e911d142fdcb00e">Add columns.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__s2da4a12267e84cebbfe1f44aec8b38d2"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">table_name</span>
<span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">compress_mode</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">COLLATE</span><span class="w"> </span><span class="k">collation</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">column_constraint</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="p">]</span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001188588994__l2397598f8e844ce0941cb6b57c6860e6">Update columns.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__sd35dfd5f0bd942848a66fa2200257ad6"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">table_name</span><span class="w"> </span>
<span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="n">data_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="n">ENABLE</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="k">column_name</span><span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="k">constraint_name</span><span class="w"> </span><span class="p">]</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="err">}</span><span class="w"> </span><span class="p">[,</span><span class="w"> </span><span class="p">...]</span><span class="w"> </span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001188588994__s3e87132692794964b56e3ba420e7b544"><a name="EN-US_TOPIC_0000001188588994__s3e87132692794964b56e3ba420e7b544"></a><a name="s3e87132692794964b56e3ba420e7b544"></a><h4 class="sectiontitle">Parameter Description</h4><ul id="EN-US_TOPIC_0000001188588994__u3ce4b0418cee4ebebb280c64ac43faa8"><li id="EN-US_TOPIC_0000001188588994__l92c275fdb8324bef914a56b717aff13b"><strong id="EN-US_TOPIC_0000001188588994__a09a40a26757347dfa890c1aafc20cd64">IF EXISTS</strong><p id="EN-US_TOPIC_0000001188588994__a23d52d39030546d182ead0c55158bdde">Sends a notification instead of an error if no tables have identical names. The notification prompts that the table you are querying does not exist.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l12968293935b40248f2867d212cb9963"><strong id="EN-US_TOPIC_0000001188588994__ab9e7a64f540c409eac3591e145f5f76a">table_name [*] | ONLY table_name | ONLY ( table_name )</strong><p id="EN-US_TOPIC_0000001188588994__a5d424ffff2d8449ba7e40f8ce8787e44"><strong id="EN-US_TOPIC_0000001188588994__b842352706151034">table_name</strong> is the name of table that you need to modify.</p>
<p id="EN-US_TOPIC_0000001188588994__a36f3090c29cc490d8cc3078256fd2c43">If <strong id="EN-US_TOPIC_0000001188588994__b84235270615116">ONLY</strong> is specified, only the table is modified. If <strong id="EN-US_TOPIC_0000001188588994__b842352706151056">ONLY</strong> is not specified, the table and all subtables will be modified. You can add the asterisk (*) option following the table name to specify that all subtables are scanned, which is the default operation.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l73ac0b67e0994f3ea75c20580bdf423d"><strong id="EN-US_TOPIC_0000001188588994__a00359be28ebd4af9b1ad8d688be2feb0">constraint_name</strong><p id="EN-US_TOPIC_0000001188588994__af8f4f90033934f179bb713ac4a872311">Name of a constraint. The constraint name can contain a maximum of 63 characters.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l375e5586d08c4aa9a7cae288983c09d8"><strong id="EN-US_TOPIC_0000001188588994__aff01e03addf649768a4aa3c882895b37">index_name</strong><p id="EN-US_TOPIC_0000001188588994__a109a8855ac224f4492c1f307aa1c986c">Specifies the name of this index.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l58424457d81c4d69b488db62f34c0e23"><strong id="EN-US_TOPIC_0000001188588994__ae1618795475542b0821573e8ecfa0c7a">storage_parameter</strong><p id="EN-US_TOPIC_0000001188588994__a29f5088843794ee6a4341331ae833b4a">Specifies the name of a storage parameter.</p>
<p id="EN-US_TOPIC_0000001188588994__p2515112613504">The following options are added for partition management:</p>
<ul id="EN-US_TOPIC_0000001188588994__ul12892854155016"><li id="EN-US_TOPIC_0000001188588994__li1989205418506"><strong id="EN-US_TOPIC_0000001188588994__b858114399453">PERIOD </strong>(interval type)<p id="EN-US_TOPIC_0000001188588994__p10892115411501">Sets the period for automatically creating partitions in partition management.</p>
<p id="EN-US_TOPIC_0000001188588994__p14892135445019">For details about the value range of <strong id="EN-US_TOPIC_0000001188588994__b129541241134912">PERIOD </strong>and the restrictions on enabling this function, see <a href="dws_06_0179.html#EN-US_TOPIC_0000001233510133__li672910401685">▪PERIOD</a>.</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note1866294814384"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul6258739114316"><li id="EN-US_TOPIC_0000001188588994__li32581839164318">If this parameter is not configured when you create a table, you can run the <strong id="EN-US_TOPIC_0000001188588994__b17630182711719">set</strong> statements to configure this parameter and enable automatic partition creation. If this parameter has been configured before, you can run the <strong id="EN-US_TOPIC_0000001188588994__b1567511130180">set</strong> statements to modify this parameter.</li><li id="EN-US_TOPIC_0000001188588994__li1725813395434">You can run the <strong id="EN-US_TOPIC_0000001188588994__b1795350171818">reset</strong> command to disable the automatic partition creation. However, if the automatic partition deletion is enabled, the automatic partition creation cannot be disabled.</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__li168923541503"><strong id="EN-US_TOPIC_0000001188588994__b2506239135">TTL </strong>(interval type)<p id="EN-US_TOPIC_0000001188588994__p989255475017">Set the partition expiration time for automatically deleting partitions in partition management.</p>
<p id="EN-US_TOPIC_0000001188588994__p13892554145015">For details about the TTL range and restrictions on enabling this function, see <a href="dws_06_0179.html#EN-US_TOPIC_0000001233510133__li49277207810">▪TTL</a>.</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note5318059144410"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001188588994__ul16318459184419"><li id="EN-US_TOPIC_0000001188588994__li1831855924413">If this parameter is not configured when you create a table, you can run the <strong id="EN-US_TOPIC_0000001188588994__b1490163016205">set</strong> statements to configure this parameter and enable automatic partition deletion. If this parameter has been configured before, you can run the <strong id="EN-US_TOPIC_0000001188588994__b849153010205">set</strong> statements to modify this parameter.</li><li id="EN-US_TOPIC_0000001188588994__li9318859134413">You can run the <strong id="EN-US_TOPIC_0000001188588994__b550916120219">reset </strong>command to disable the automatic partition deletion.</li></ul>
</div></div>
</li></ul>
</li><li id="EN-US_TOPIC_0000001188588994__l44ea9b8aafa64e4eaee32a92c8315147"><strong id="EN-US_TOPIC_0000001188588994__a28f26c1f6c024610bd3980a3fd71fb36">new_owner</strong><p id="EN-US_TOPIC_0000001188588994__aac27200baaec429ba6554b864b7924f3">Specifies the name of the new table owner.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l5d4c93c751894da284c4af12757f1256"><strong id="EN-US_TOPIC_0000001188588994__ab9c72d73dee0404ca55714f5071e376e">new_tablespace</strong><p id="EN-US_TOPIC_0000001188588994__a50dc9a6e169347e7a82267fddb5cd206">Specifies the new name of the tablespace to which the table belongs.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l78e158e02c834b388c19bcbaafc87ab8"><strong id="EN-US_TOPIC_0000001188588994__en-us_topic_0059779051_a8edb55d3b00d4f07aafbbcd02b681502">column_name</strong>, <strong id="EN-US_TOPIC_0000001188588994__b1082413103473">column_1_name</strong>, <strong id="EN-US_TOPIC_0000001188588994__b68128172477">column_2_name</strong><p id="EN-US_TOPIC_0000001188588994__af6d1dd7326734b788dd61039d87e3b88">Specifies the name of a new or an existing column.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l5e059a3f54c34652904a82b192f27000"><strong id="EN-US_TOPIC_0000001188588994__a1624e5f2d3c741db876b0a95fd2a2843">data_type</strong><p id="EN-US_TOPIC_0000001188588994__aaa794ac7869146dabb2895a80dc4ed44">Specifies the type of a new column or a new type of an existing column.</p>
</li><li id="EN-US_TOPIC_0000001188588994__le73c1ebcf3834f2ebad246395398e95a"><strong id="EN-US_TOPIC_0000001188588994__a6a696f97ff174853a497bf0728f01c5a">compress_mode</strong><p id="EN-US_TOPIC_0000001188588994__a78ba5f916ce94229a210ca8cc8de5c17">Specifies the compress options of the table, only available for row-based tables. The clause specifies the algorithm preferentially used by the column.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l00b9cb960bde4b7bae88f5343ca78cdf"><strong id="EN-US_TOPIC_0000001188588994__a65eacaf7461c421e9d8b7814b444f9b1">collation</strong><p id="EN-US_TOPIC_0000001188588994__ae3b611936e5b425286dd4421a234a363">Specifies the collation rule name of a column. The optional <strong id="EN-US_TOPIC_0000001188588994__b7850141194811">COLLATE</strong> clause specifies a collation for the new column; if omitted, the collation is the default for the new column.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li1863216543374"><strong id="EN-US_TOPIC_0000001188588994__b11975175583717">USING expression</strong><p id="EN-US_TOPIC_0000001188588994__p149311312123815">A <strong id="EN-US_TOPIC_0000001188588994__b11182019145315">USING</strong> clause specifies how to compute the new column value from the old; if omitted, the default conversion is an assignment cast from old data type to new. A <strong id="EN-US_TOPIC_0000001188588994__b14347931105313">USING</strong> clause must be provided if there is no implicit or assignment cast from the old to new type.</p>
<div class="note" id="EN-US_TOPIC_0000001188588994__note13845185263813"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001188588994__p38451752183820"><strong id="EN-US_TOPIC_0000001188588994__b12911114217533">USING</strong> in <strong id="EN-US_TOPIC_0000001188588994__b8911174214535">ALTER TYPE</strong> can specify any expression involving the old values of the row; that is, it can refer to any columns other than the one being converted. This allows very general conversions to be done with the <strong id="EN-US_TOPIC_0000001188588994__b77934204094049">ALTER TYPE</strong> syntax. Because of this flexibility, the <strong id="EN-US_TOPIC_0000001188588994__b829503165618">USING</strong> expression is not applied to the column's default value (if any); the result might not be a constant expression as required for a default. This means that when there is no implicit or assignment cast from old to new type, <strong id="EN-US_TOPIC_0000001188588994__b49763894694049">ALTER TYPE</strong> might fail to convert the default even though a <strong id="EN-US_TOPIC_0000001188588994__b177217868794049">USING</strong> clause is supplied. In such cases, drop the default with <strong id="EN-US_TOPIC_0000001188588994__b102013567794049">DROP DEFAULT</strong>, perform the <strong id="EN-US_TOPIC_0000001188588994__b142048839394049">ALTER TYPE</strong>, and then use <strong id="EN-US_TOPIC_0000001188588994__b97611542494049">SET DEFAULT</strong> to add a suitable new default. Similar considerations apply to indexes and constraints involving the column.</p>
</div></div>
</li><li id="EN-US_TOPIC_0000001188588994__lb6141d54e5cc41eda27abd108afbcfcb"><strong id="EN-US_TOPIC_0000001188588994__a737005f2007e462cbe55b33fff24f14a">NOT NULL | NULL</strong><p id="EN-US_TOPIC_0000001188588994__a69b6a80d440b4935ad8c6794a2a85bed">Sets whether the column allows null values.</p>
</li><li id="EN-US_TOPIC_0000001188588994__lc4b111665b104c469a6e029fb850a154"><strong id="EN-US_TOPIC_0000001188588994__a8c5854120562410095f44d26fbcdea03">integer</strong><p id="EN-US_TOPIC_0000001188588994__abaf0c7e0500c4736b52449fabcbb98a5">Specifies the constant value of an integer with a sign. If <strong id="EN-US_TOPIC_0000001188588994__b89281617145618">PERCENT</strong> is used, the range of <strong id="EN-US_TOPIC_0000001188588994__b192915176560">integer</strong> is from 0 to 100.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l07f1613a57ab484393edc74542c96fcd"><strong id="EN-US_TOPIC_0000001188588994__a34c195a2cc8c446482c0ec1d82f0c0a4">attribute_option</strong><p id="EN-US_TOPIC_0000001188588994__a506e545250e0445e91caa97cc7daa614">Specifies an attribute option.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li5497182810713"><strong id="EN-US_TOPIC_0000001188588994__b93206231174">PLAIN | EXTERNAL | EXTENDED | MAIN</strong><p id="EN-US_TOPIC_0000001188588994__p1588010584718">Specifies a column storage mode.</p>
<ul id="EN-US_TOPIC_0000001188588994__ul711394913816"><li id="EN-US_TOPIC_0000001188588994__li955210451285"><strong id="EN-US_TOPIC_0000001188588994__b284193435618">PLAIN</strong> must be used for fixed-length values (such as integers). It must be inline and uncompressed.</li><li id="EN-US_TOPIC_0000001188588994__li174261251388"><strong id="EN-US_TOPIC_0000001188588994__b39489616094049">MAIN</strong> is for inline, compressible data.</li><li id="EN-US_TOPIC_0000001188588994__li236116539813"><strong id="EN-US_TOPIC_0000001188588994__b126796620894049">EXTERNAL</strong> is for external, uncompressed data. Use of <strong id="EN-US_TOPIC_0000001188588994__b61890978894049">EXTERNAL</strong> will make substring operations on <strong id="EN-US_TOPIC_0000001188588994__b33200389094049">text</strong> and <strong id="EN-US_TOPIC_0000001188588994__b111431762794049">bytea</strong> values run faster, at the penalty of increased storage space.</li><li id="EN-US_TOPIC_0000001188588994__li1332312553811"><strong id="EN-US_TOPIC_0000001188588994__b18749454165613">EXTENDED</strong> is for external, compressed data. <strong id="EN-US_TOPIC_0000001188588994__b1375045415612">EXTENDED</strong> is the default for most data types that support non-<strong id="EN-US_TOPIC_0000001188588994__b77501954185611">PLAIN</strong> storage.</li></ul>
</li><li id="EN-US_TOPIC_0000001188588994__l147db00f461543e09adfe4572485c249"><strong id="EN-US_TOPIC_0000001188588994__a1a47f37d64c544bf93ff77f84ecb74d6">CHECK ( expression )</strong><p id="EN-US_TOPIC_0000001188588994__a40d4e58463ed40b1b496bf1c13282b57">New or updated rows must satisfy for an insert or update operation to succeed. Expressions evaluating to TRUE succeed. If any row of an insert or update operation produces a FALSE result, an error exception is raised and the insert or update does not alter the database.</p>
<p id="EN-US_TOPIC_0000001188588994__adecb9e6117344ccdbbfc0182b7f03f24">A check constraint specified as a column constraint should reference only the column's values, while an expression appearing in a table constraint can reference multiple columns.</p>
<p id="EN-US_TOPIC_0000001188588994__ab96083ce42b441839f63d093c8120810">Currently, <strong id="EN-US_TOPIC_0000001188588994__b842352706151134">CHECK</strong> expression does not include subqueries and cannot use variables apart from the current column.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l5a049cf9caf84904a5173eff361e4e79"><strong id="EN-US_TOPIC_0000001188588994__a0dc5630f2da0486b9c110bd8847fabcf">DEFAULT default_expr</strong><p id="EN-US_TOPIC_0000001188588994__a9661094f1eb7437a8b9e7085c4534e76">Assigns a default data value for a column. </p>
<p id="EN-US_TOPIC_0000001188588994__aa315f6f2e7e141b49f97b90f241656c0">The data type of the default expression must match the data type of the column.</p>
<p id="EN-US_TOPIC_0000001188588994__ac7a4ea8afeb14fd4a5f2442ba7db691b">The default expression will be used in any insert operation that does not specify a value for the column. If there is no default value for a column, then the default value is <strong id="EN-US_TOPIC_0000001188588994__b842352706104725">NULL</strong>.</p>
<p id="EN-US_TOPIC_0000001188588994__p6999550839">If a suffix operator, such as (!), is used in <strong id="EN-US_TOPIC_0000001188588994__b151238111813">default_expr</strong>, enclose the operator in parentheses.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l7aa4802c024642a09e3d96463a1e1573"><strong id="EN-US_TOPIC_0000001188588994__ada92b1e0cb764a439679282c5dfe83a1">UNIQUE index_parameters</strong><p id="EN-US_TOPIC_0000001188588994__acd007fb480d6498bb4d416f75f601c25"><strong id="EN-US_TOPIC_0000001188588994__ab583861fce43490993f940604336d5f0">UNIQUE ( column_name [, ... ] ) index_parameters</strong></p>
<p id="EN-US_TOPIC_0000001188588994__abbc43b58130b43bf83f6614ec938b7aa">The <strong id="EN-US_TOPIC_0000001188588994__b2533867716167">UNIQUE</strong> constraint specifies that a group of one or more columns of a table can contain only unique values.</p>
</li><li id="EN-US_TOPIC_0000001188588994__lc3ec41d6b71b479b99562bb3dc9f690b"><strong id="EN-US_TOPIC_0000001188588994__a8d4f1f7acd06469784c7b130dc4129af">PRIMARY KEY index_parameters</strong><p id="EN-US_TOPIC_0000001188588994__a9669ae2ff1b24cc3881351f37b019722"><strong id="EN-US_TOPIC_0000001188588994__abb164bfc5c2b448ebf4b3cb0dbb22850">PRIMARY KEY ( column_name [, ... ] ) index_parameters</strong></p>
<p id="EN-US_TOPIC_0000001188588994__aa05d9cd909274ec9a709a38a9933fc63">The primary key constraint specifies that a column or columns of a table can contain only unique (non-duplicate) and non-null values.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l7598c25d351c401bb6c29194dc0b9a11"><strong id="EN-US_TOPIC_0000001188588994__ad00eb3ae1d634b3084fe52daf8667e85">DEFERRABLE | NOT DEFERRABLE | INITIALLY DEFERRED | INITIALLY IMMEDIATE</strong><p id="EN-US_TOPIC_0000001188588994__a4cf9067159cd4d60a7defb8a0b25e7cc">Sets whether the constraint is deferrable. This option is unavailable to column-store tables.</p>
<ul id="EN-US_TOPIC_0000001188588994__u5acfddaa62c847cea0b3ba702807309c"><li id="EN-US_TOPIC_0000001188588994__leb16ac3ca2064db581d750b6dd028a9f"><strong id="EN-US_TOPIC_0000001188588994__b84235270614310">DEFERRABLE</strong>: deferrable can be postponed until the end of the transaction using the <strong id="EN-US_TOPIC_0000001188588994__b60118629161614">SET CONSTRAINTS</strong> command.</li><li id="EN-US_TOPIC_0000001188588994__lc8b89d3e4cf34a5197766c56772359fe"><strong id="EN-US_TOPIC_0000001188588994__b842352706151327">NOT DEFERRABLE</strong>: checks immediately after the execution of each command.</li><li id="EN-US_TOPIC_0000001188588994__lb38080109cc544129029ca56a6508ecb"><strong id="EN-US_TOPIC_0000001188588994__b842352706151332">INITIALLY IMMEDIATE</strong>: checks immediately after the execution of each statement.</li><li id="EN-US_TOPIC_0000001188588994__lf6787cc384f345869e3c358a02f8edbf"><strong id="EN-US_TOPIC_0000001188588994__b842352706151337">INITIALLY DEFERRED</strong>: checks when the transaction ends.</li></ul>
</li><li id="EN-US_TOPIC_0000001188588994__l0ac03e91a3ab444a926a0779ef761b17"><strong id="EN-US_TOPIC_0000001188588994__a2357028c6ad444488ae16e01101a6ba6">WITH ( {storage_parameter = value} [, ... ] )</strong><p id="EN-US_TOPIC_0000001188588994__a39d971beeaaa448cbb5708ab894c4fd7">Specifies an optional storage parameter for a table or an index.</p>
</li><li id="EN-US_TOPIC_0000001188588994__li7246155185418"><strong id="EN-US_TOPIC_0000001188588994__b15956141105416">COMPRESS|NOCOMPRESS</strong><ul id="EN-US_TOPIC_0000001188588994__u57b319a17607468a97eec9c233a8af76"><li id="EN-US_TOPIC_0000001188588994__l7250255b368f4362a8ab18cabbf67c27"><strong id="EN-US_TOPIC_0000001188588994__b59962056394049">NOCOMPRESS</strong>: If the <strong id="EN-US_TOPIC_0000001188588994__b180330568694049">NOCOMPRESS</strong> keyword is specified, the existing compression feature of the table is not changed.</li><li id="EN-US_TOPIC_0000001188588994__l15d0e1ad7f3a4fb9b9031e78787356ca"><strong id="EN-US_TOPIC_0000001188588994__b141434941594049">COMPRESS</strong>: If the <strong id="EN-US_TOPIC_0000001188588994__b140717693894049">COMPRESS</strong> keyword is specified, the table compression feature is triggered if tuples are inserted in a batch.</li></ul>
</li><li id="EN-US_TOPIC_0000001188588994__l20c113f1fe3d4b0b9fae03ac86b74adc"><strong id="EN-US_TOPIC_0000001188588994__afd71ca7022f34dcda6901e7896af57b9">new_table_name</strong><p id="EN-US_TOPIC_0000001188588994__a08467baa248044a0864387ef9b56303b">Specifies the new table name.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l1548382d3e524c739714ee6bcf6f4910"><strong id="EN-US_TOPIC_0000001188588994__a0c2b8855f14045338cdce3b642b800ce">new_column_name</strong><p id="EN-US_TOPIC_0000001188588994__afe2134ea300c410aad808f657c3ec739">Specifies the new name of a specific column in a table.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l784160a50b8943af89e1e48ec672dbfb"><strong id="EN-US_TOPIC_0000001188588994__ac977bcfeadc64040bae22f6da64dd469">new_constraint_name</strong><p id="EN-US_TOPIC_0000001188588994__ab2a3f027ea504410b3c9f7256f013cfa">Specifies the new name of a table constraint.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l7ae326cb75a1408abdb74f6779d6cbb9"><strong id="EN-US_TOPIC_0000001188588994__a3fb32699552a46a49670f2e8e2a530fe">new_schema</strong><p id="EN-US_TOPIC_0000001188588994__ad01a1b95e13a41ab987e978dc2b6dd92">Specifies the new schema name.</p>
</li><li id="EN-US_TOPIC_0000001188588994__l470a8ea3981f4b01bc598f55c7c10364"><strong id="EN-US_TOPIC_0000001188588994__afef4eb0390e84aeaaff08339c1f80d9b">CASCADE</strong><p id="EN-US_TOPIC_0000001188588994__ab0674dc50b3744f381e5f14bf86ce87b">Automatically drops objects that depend on the dropped column or constraint (for example, views referencing the column).</p>
</li><li id="EN-US_TOPIC_0000001188588994__ld7422b30ff314c589135f2bb9a8f676e"><strong id="EN-US_TOPIC_0000001188588994__a5b9c248884d64c1aa9e51d055e930c0d">RESTRICT</strong><p id="EN-US_TOPIC_0000001188588994__a1a04e6ada66c40399bc40212cd04534f">Refuses to drop the column or constraint if there are any dependent objects. This is the default behavior.</p>
</li><li id="EN-US_TOPIC_0000001188588994__lc141c7a481bc4fc3b64429b5af27004a"><strong id="EN-US_TOPIC_0000001188588994__a2553541e8cd54c8fac76be2820f873df">schema_name</strong><p id="EN-US_TOPIC_0000001188588994__aef2a44f7091d44188981c051bcd64766">Specifies the schema name of a table.</p>
</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001188588994__section1781491882412"><h4 class="sectiontitle">Table Operation Examples</h4><div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen7206193511575"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DROP</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="p">;</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span>
<span class="p">(</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_CUSTKEY</span><span class="w"> </span><span class="nb">BIGINT</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_NAME</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">25</span><span class="p">)</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_ADDRESS</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">40</span><span class="p">)</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_NATIONKEY</span><span class="w"> </span><span class="nb">INT</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_PHONE</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">15</span><span class="p">)</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">C_ACCTBAL</span><span class="w"> </span><span class="nb">DECIMAL</span><span class="p">(</span><span class="mi">15</span><span class="p">,</span><span class="mi">2</span><span class="p">)</span>
<span class="p">)</span>
<span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="p">(</span><span class="n">C_CUSTKEY</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1562754692417">Adds primary key constraint or unique constraint based on the unique index.</p>
<p id="EN-US_TOPIC_0000001188588994__p11627946152417">Create an index <strong id="EN-US_TOPIC_0000001188588994__b202128080112639">CUSTOMER_constraint1</strong> for the table <strong id="EN-US_TOPIC_0000001188588994__b1371064613112639">CUSTOMER</strong>. Then add primary key constraints, and rename the created index.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1754016379266"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">CUSTOMER_constraint1</span><span class="w"> </span><span class="k">ON</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="p">(</span><span class="n">C_CUSTKEY</span><span class="p">);</span>
<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">CUSTOMER_constraint2</span><span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="k">USING</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">CUSTOMER_constraint1</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p663019468240">Rename a table constraint:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1194163112264"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">CUSTOMER_constraint2</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">CUSTOMER_constraint</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p46301946102414">Delete a table constraint:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen15549142713262"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">CUSTOMER_constraint</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1463016465243">Add a table index:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen121681224172613"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">CUSTOMER_index</span><span class="p">(</span><span class="n">C_CUSTKEY</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1963084642419">Delete a table index:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen19361819142617"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">INDEX</span><span class="w"> </span><span class="n">CUSTOMER_index</span><span class="p">;</span>
<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">KEY</span><span class="w"> </span><span class="n">CUSTOMER_index</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p12983184164218">Add an index to a column in the table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen29839417426"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="n">c_address_id</span><span class="w"> </span><span class="nb">varchar</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">ca_address_index</span><span class="w"> </span><span class="k">CHECK</span><span class="w"> </span><span class="p">(</span><span class="n">c_address_id</span><span class="w"> </span><span class="o">&gt;</span><span class="w"> </span><span class="mi">0</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p126411822181411">Add a primary key constraint to the table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen6900613104210"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="p">(</span><span class="n">C_CUSTKEY</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1367174431712">Rename a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen103672442178"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">CUSTOMER</span><span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">CUSTOMER_t</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p8282182315176">Create a column-store table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1215719587599"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DROP</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="n">customer_address</span><span class="p">;</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span>
<span class="p">(</span>
<span class="w"> </span><span class="n">ca_address_sk</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">ca_address_id</span><span class="w"> </span><span class="nb">CHARACTER</span><span class="p">(</span><span class="mi">16</span><span class="p">)</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">ca_street_number</span><span class="w"> </span><span class="nb">CHARACTER</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">ca_street_name</span><span class="w"> </span><span class="nb">CHARACTER</span><span class="w"> </span><span class="nb">varying</span><span class="p">(</span><span class="mi">60</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">ca_street_type</span><span class="w"> </span><span class="nb">CHARACTER</span><span class="p">(</span><span class="mi">15</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">ca_suite_number</span><span class="w"> </span><span class="nb">CHARACTER</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span>
<span class="p">)</span>
<span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="n">ORIENTATION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">COLUMN</span><span class="p">,</span><span class="w"> </span><span class="n">COMPRESSION</span><span class="o">=</span><span class="n">HIGH</span><span class="p">,</span><span class="n">COLVERSION</span><span class="o">=</span><span class="mi">2</span><span class="p">.</span><span class="mi">0</span><span class="p">)</span>
<span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="n">ca_address_sk</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p2063124652410">Add a partial cluster key to a column-store table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen3198136261"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">customer_address_cluster</span><span class="w"> </span><span class="k">PARTIAL</span><span class="w"> </span><span class="k">CLUSTER</span><span class="w"> </span><span class="k">KEY</span><span class="p">(</span><span class="n">ca_address_sk</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1463154618243">Delete a partial cluster key from the column-store table.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen18518694269"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">CONSTRAINT</span><span class="w"> </span><span class="n">customer_address_cluster</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1563194642417">Switch the storage format of a column-store table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen2880458267"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="p">(</span><span class="n">COLVERSION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1</span><span class="p">.</span><span class="mi">0</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p5631184615244">Change the distribution mode of a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen14515122112618"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span><span class="w"> </span><span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">REPLICATION</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<div class="p" id="EN-US_TOPIC_0000001188588994__p106311146192418">Change the schema of a table:<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen869818581253"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">tpcds</span><span class="p">;</span>
<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_address</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">tpcds</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p13631174610241">Change the data temperature for a single table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen104672652513"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span>
<span class="normal">12</span>
<span class="normal">13</span>
<span class="normal">14</span>
<span class="normal">15</span>
<span class="normal">16</span>
<span class="normal">17</span>
<span class="normal">18</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DROP</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="n">cold_hot_table</span><span class="p">;</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">cold_hot_table</span><span class="p">(</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_ID</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">16</span><span class="p">)</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_NAME</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_STREET_NUMBER</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_STREET_NAME</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">60</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_STREET_ID</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">15</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_SUITE_NUMBER</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span><span class="p">)</span>
<span class="k">WITH</span><span class="w"> </span><span class="p">(</span><span class="n">ORIENTATION</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="k">COLUMN</span><span class="p">,</span><span class="w"> </span><span class="n">storage_policy</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s1">'LMT:30'</span><span class="p">)</span>
<span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="n">W_WAREHOUSE_ID</span><span class="p">)</span>
<span class="n">PARTITION</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">RANGE</span><span class="p">(</span><span class="n">W_STREET_ID</span><span class="p">)(</span>
<span class="w"> </span><span class="n">PARTITION</span><span class="w"> </span><span class="n">P1</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="k">LESS</span><span class="w"> </span><span class="k">THAN</span><span class="p">(</span><span class="mi">100000</span><span class="p">),</span>
<span class="w"> </span><span class="n">PARTITION</span><span class="w"> </span><span class="n">P2</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="k">LESS</span><span class="w"> </span><span class="k">THAN</span><span class="p">(</span><span class="mi">200000</span><span class="p">),</span>
<span class="w"> </span><span class="n">PARTITION</span><span class="w"> </span><span class="n">P3</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="k">LESS</span><span class="w"> </span><span class="k">THAN</span><span class="p">(</span><span class="mi">300000</span><span class="p">),</span>
<span class="w"> </span><span class="n">PARTITION</span><span class="w"> </span><span class="n">P4</span><span class="w"> </span><span class="k">VALUES</span><span class="w"> </span><span class="k">LESS</span><span class="w"> </span><span class="k">THAN</span><span class="p">(</span><span class="k">MAXVALUE</span><span class="p">)</span>
<span class="p">)</span><span class="n">ENABLE</span><span class="w"> </span><span class="k">ROW</span><span class="w"> </span><span class="n">MOVEMENT</span><span class="p">;</span>
<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">cold_hot_table</span><span class="w"> </span><span class="n">REFRESH</span><span class="w"> </span><span class="k">STORAGE</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p1127125314463">Change a column-store partitioned table to a hot and cold table.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen2592040484"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span>
<span class="normal">7</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">table</span><span class="w"> </span><span class="n">test_1</span><span class="p">(</span><span class="n">id</span><span class="w"> </span><span class="nb">int</span><span class="p">,</span><span class="n">d_time</span><span class="w"> </span><span class="nb">date</span><span class="p">)</span>
<span class="k">WITH</span><span class="p">(</span><span class="n">ORIENTATION</span><span class="o">=</span><span class="k">COLUMN</span><span class="p">)</span>
<span class="n">DISTRIBUTE</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">HASH</span><span class="w"> </span><span class="p">(</span><span class="n">id</span><span class="p">)</span>
<span class="n">PARTITION</span><span class="w"> </span><span class="k">BY</span><span class="w"> </span><span class="n">RANGE</span><span class="w"> </span><span class="p">(</span><span class="n">d_time</span><span class="p">)</span>
<span class="p">(</span><span class="n">PARTITION</span><span class="w"> </span><span class="n">p1</span><span class="w"> </span><span class="k">START</span><span class="p">(</span><span class="s1">'2022-01-01'</span><span class="p">)</span><span class="w"> </span><span class="k">END</span><span class="p">(</span><span class="s1">'2022-01-31'</span><span class="p">)</span><span class="w"> </span><span class="k">EVERY</span><span class="p">(</span><span class="nb">interval</span><span class="w"> </span><span class="s1">'1 day'</span><span class="p">));</span>
<span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">test_1</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="p">(</span><span class="n">storage_policy</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s1">'LMT:100'</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001188588994__section19120102812419"><h4 class="sectiontitle">Column Operation Examples</h4><div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen021814161104"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
<span class="normal"> 2</span>
<span class="normal"> 3</span>
<span class="normal"> 4</span>
<span class="normal"> 5</span>
<span class="normal"> 6</span>
<span class="normal"> 7</span>
<span class="normal"> 8</span>
<span class="normal"> 9</span>
<span class="normal">10</span>
<span class="normal">11</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">DROP</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="k">IF</span><span class="w"> </span><span class="k">EXISTS</span><span class="w"> </span><span class="n">warehouse_t</span><span class="p">;</span>
<span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span>
<span class="p">(</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_SK</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_ID</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">16</span><span class="p">)</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_NAME</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="w"> </span><span class="k">UNIQUE</span><span class="w"> </span><span class="k">DEFERRABLE</span><span class="p">,</span>
<span class="w"> </span><span class="n">W_WAREHOUSE_SQ_FT</span><span class="w"> </span><span class="nb">INTEGER</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_COUNTY</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">30</span><span class="p">)</span><span class="w"> </span><span class="p">,</span>
<span class="w"> </span><span class="n">W_STATE</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">2</span><span class="p">)</span><span class="w"> </span><span class="k">DEFAULT</span><span class="w"> </span><span class="s1">'GA'</span><span class="p">,</span>
<span class="w"> </span><span class="n">W_ZIP</span><span class="w"> </span><span class="nb">CHAR</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="w"> </span>
<span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p14788155713243">Add a column to a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen14715192412812"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="n">W_GOODS_CATEGORY</span><span class="w"> </span><span class="nb">int</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p97881757112416">Modify the column name and column field information in the table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen17550152122818"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="n">CHANGE</span><span class="w"> </span><span class="n">W_GOODS_CATEGORY</span><span class="w"> </span><span class="n">W_GOODS_CATEGORY2</span><span class="w"> </span><span class="nb">DECIMAL</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="w"> </span><span class="k">COMMENT</span><span class="w"> </span><span class="s1">'W_GOODS_CATEGORY'</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p6788657102411">Add a primary key to a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen76619183281"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="k">PRIMARY</span><span class="w"> </span><span class="k">KEY</span><span class="p">(</span><span class="n">w_warehouse_name</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p13788135752417">Rename a column:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1341791519288"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">RENAME</span><span class="w"> </span><span class="n">W_ZIP</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="n">new_W_ZIP</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p10788357122410">Add columns to a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1250631162813"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">ADD</span><span class="w"> </span><span class="p">(</span><span class="n">W_COMMENT</span><span class="w"> </span><span class="nb">VARCHAR</span><span class="p">(</span><span class="mi">117</span><span class="p">)</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">,</span><span class="w"> </span><span class="n">W_COUNT</span><span class="w"> </span><span class="nb">int</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p778813579249">Change the data type of a column in the table and set the column constraint to <strong id="EN-US_TOPIC_0000001188588994__b1498410101112639">NOT NULL</strong>:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen979457142810"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">MODIFY</span><span class="w"> </span><span class="n">W_WAREHOUSE_SQ_FT</span><span class="w"> </span><span class="nb">varchar</span><span class="p">(</span><span class="mi">20</span><span class="p">)</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p177881572244">Add the NOT NULL constraint to a certain column in the table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen1028614417281"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">ALTER</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="n">W_COUNTY</span><span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="k">NOT</span><span class="w"> </span><span class="k">NULL</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
<p id="EN-US_TOPIC_0000001188588994__p0788135718245">Delete a column from a table:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001188588994__screen162761915282"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">ALTER</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">warehouse_t</span><span class="w"> </span><span class="k">DROP</span><span class="w"> </span><span class="k">COLUMN</span><span class="w"> </span><span class="n">W_STATE</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001188588994__sa250a7b963584d40ab1c72b2fb1874bc"><h4 class="sectiontitle">Helpful Links</h4><p id="EN-US_TOPIC_0000001188588994__a312a948c506a47408306c670d4b9880c"><a href="dws_06_0177.html">CREATE TABLE</a>, <a href="dws_06_0276.html">12.101-RENAME TABLE</a>, and <a href="dws_06_0208.html">DROP TABLE</a></p>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_06_0118.html">DDL Syntax</a></div>
</div>
</div>
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