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doc-exports/docs/dws/dev/dws_06_0367.html
luhuayi 177cd61a57 DWS DEVG 910.211 version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Co-authored-by: luhuayi <luhuayi@huawei.com>
Co-committed-by: luhuayi <luhuayi@huawei.com>
2025-05-05 07:44:03 +00:00

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<a name="EN-US_TOPIC_0000001764675406"></a><a name="EN-US_TOPIC_0000001764675406"></a>
<h1 class="topictitle1">CREATE EXTERNAL SCHEMA</h1>
<div id="body0000001674929873"><div class="section" id="EN-US_TOPIC_0000001764675406__s628a72e4ad6147cf9cc089febf125678"><h4 class="sectiontitle">Function</h4><p id="EN-US_TOPIC_0000001764675406__en-us_topic_0059777945_p549110246542">Creates an EXTERNAL schema. This syntax is supported only in 8.3.0 and later versions.</p>
<p id="EN-US_TOPIC_0000001764675406__p8371953165819">The external schema is used to access tables of the LakeFormation, DLI, or HMS service. You can use an external schema name as the prefix for access. If there is no schema name prefix, you can access the named objects in the current schema.</p>
</div>
<div class="section" id="EN-US_TOPIC_0000001764675406__sd8a756b505184705a8897156f5eb52c1"><h4 class="sectiontitle">Precautions</h4><ul id="EN-US_TOPIC_0000001764675406__ul795312913276"><li id="EN-US_TOPIC_0000001764675406__li1778419551026">A user who has the CREATE permission on the current database can create a foreign schema.</li><li id="EN-US_TOPIC_0000001764675406__li193062313818">When creating a named object, do not use EXTERNAL SCHEMA as the prefix. Objects cannot be created in EXTERNAL SCHEMA.</li><li id="EN-US_TOPIC_0000001764675406__li496317248211"><strong id="EN-US_TOPIC_0000001764675406__b243033611309">CREATE EXTERNAL SCHEMA</strong> does not support subcommands for creating objects in the new schema.</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001764675406__s6d289579f18149c1a17ec06712dde98a"><h4 class="sectiontitle">Syntax</h4><ul id="EN-US_TOPIC_0000001764675406__ueb686891603d403480637aa0cf189f2c"><li id="EN-US_TOPIC_0000001764675406__la0976fa1070d4c8b9088a4ed573350f2">Create an external schema with a specified name.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__sa863f654e9d44d4f9bbc808b7ee28222"><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="k">CREATE</span><span class="w"> </span><span class="k">EXTERNAL</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="k">schema_name</span><span class="w"> </span>
<span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="k">SOURCE</span><span class="w"> </span><span class="n">source_name</span>
<span class="w"> </span><span class="k">DATABASE</span><span class="w"> </span><span class="s1">'database_name'</span>
<span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="k">server_name</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">CATALOG</span><span class="w"> </span><span class="s1">'catalog_name'</span><span class="w"> </span><span class="p">]</span>
<span class="w"> </span><span class="p">[</span><span class="w"> </span><span class="k">OPTIONS</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="err">{</span><span class="w"> </span><span class="n">option_name</span><span class="w"> </span><span class="s1">' 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="p">[</span><span class="n">METAADDRESS</span><span class="w"> </span><span class="s1">'address'</span><span class="p">]</span>
<span class="w"> </span><span class="p">[</span><span class="n">CONFIGURATION</span><span class="w"> </span><span class="s1">'confpath'</span><span class="p">];</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001764675406__s137c7d80e527499da3008e35aa5115aa"><h4 class="sectiontitle">Parameter Description</h4><ul id="EN-US_TOPIC_0000001764675406__ub308d7ce1ea94a509a9fa185772ce356"><li id="EN-US_TOPIC_0000001764675406__lf6df67d8504e48428af0f53cf4ced03f"><strong id="EN-US_TOPIC_0000001764675406__af0784a43101c4e78b5083c98d58a40c0">schema_name</strong><p id="EN-US_TOPIC_0000001764675406__a2115acd4630e42e78f9032aef52c2541">Name of an external schema.</p>
<p id="EN-US_TOPIC_0000001764675406__p6464956975">Value range: a string. It must comply with the naming convention.</p>
<div class="notice" id="EN-US_TOPIC_0000001764675406__n7c79f5a45287445cbd1241ff5145bad7"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="EN-US_TOPIC_0000001764675406__ul264217354"><li id="EN-US_TOPIC_0000001764675406__li76421971156">The name must be unique.</li><li id="EN-US_TOPIC_0000001764675406__li14982992514">The name cannot start with <strong id="EN-US_TOPIC_0000001764675406__b85208432910368">pg_</strong>.</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001764675406__l4676a2dbfd484819858b12ad8e546b30"><strong id="EN-US_TOPIC_0000001764675406__b163911791511">SOURCE</strong><p id="EN-US_TOPIC_0000001764675406__a724c2de5a7b34ea384d2b497c9ad0bd7">Type of the external metadata storage engine. Currently, <strong id="EN-US_TOPIC_0000001764675406__b187534318173">source_type</strong> can only be <strong id="EN-US_TOPIC_0000001764675406__b208751443131712">dli</strong>, <strong id="EN-US_TOPIC_0000001764675406__b1787564381713">lakeformation</strong>, or <strong id="EN-US_TOPIC_0000001764675406__b4875174313171">hive</strong>.</p>
</li><li id="EN-US_TOPIC_0000001764675406__li1566194263915"><strong id="EN-US_TOPIC_0000001764675406__b16156192815214">DATABASE</strong><p id="EN-US_TOPIC_0000001764675406__p6212172212213">Database corresponding to the external schema.</p>
</li><li id="EN-US_TOPIC_0000001764675406__lc1d779f3255e4b9cb81d8d0f7b549d7a"><strong id="EN-US_TOPIC_0000001764675406__b164835227572">SERVER</strong><p id="EN-US_TOPIC_0000001764675406__a31a7e8559d684565ad276e5c3ef84714">Value range: an existing foreign server whose type is <strong id="EN-US_TOPIC_0000001764675406__b83481448191718">lf</strong>, <strong id="EN-US_TOPIC_0000001764675406__b123485483176">dli</strong>, <strong id="EN-US_TOPIC_0000001764675406__b43483484174">obs</strong>, or <strong id="EN-US_TOPIC_0000001764675406__b183491148201715">hdfs</strong>.</p>
<p id="EN-US_TOPIC_0000001764675406__p1062844012312">You can associate an external schema with a foreign server to access external data.</p>
</li><li id="EN-US_TOPIC_0000001764675406__li3810949135815"><strong id="EN-US_TOPIC_0000001764675406__b104815304319">CATALOG</strong><p id="EN-US_TOPIC_0000001764675406__p184236126595">Catalog to be accessed in LakeFormation. This parameter is mandatory only when server type is set to <strong id="EN-US_TOPIC_0000001764675406__b11375851813">lf</strong>.</p>
</li><li id="EN-US_TOPIC_0000001764675406__li935424519181"><strong id="EN-US_TOPIC_0000001764675406__b0343205663611">OPTIONS</strong><p id="EN-US_TOPIC_0000001764675406__a9a2e0b7ef7ee45d2b5b0ca470b8bdc5c">Specifies the following parameters for a foreign table: This function is supported only by 8.3.0 and later versions.</p>
<p id="EN-US_TOPIC_0000001764675406__p1156744715350">dli_project_id</p>
<p id="EN-US_TOPIC_0000001764675406__p5391433311">Specifies the project ID corresponding to DLI. You can obtain the project ID from the management console. This parameter is available only when the server type is DLI.</p>
</li><li id="EN-US_TOPIC_0000001764675406__li821018444106"><strong id="EN-US_TOPIC_0000001764675406__b142896257538">METAADDRESS</strong><p id="EN-US_TOPIC_0000001764675406__p18862258181018">Hivemetastore communication interface. This parameter is supported only by 9.1.0 and later versions.</p>
</li><li id="EN-US_TOPIC_0000001764675406__li596751211116"><strong id="EN-US_TOPIC_0000001764675406__b961262716531">CONFIGURATION</strong><div class="p" id="EN-US_TOPIC_0000001764675406__p1527642218111">Path for storing <strong id="EN-US_TOPIC_0000001764675406__b1797921014316">hivemetastore</strong> configuration files. This parameter is supported only by 9.1.0 and later versions.<div class="note" id="EN-US_TOPIC_0000001764675406__note81791421121112"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001764675406__p1217914210114">If objects in the schema on the current search path are with the same name, specify the schemas different objects are in. You can run the <strong id="EN-US_TOPIC_0000001764675406__b90324668510368">SHOW SEARCH_PATH</strong> command to check the schemas on the current search path.</p>
</div></div>
</div>
</li></ul>
</div>
<div class="section" id="EN-US_TOPIC_0000001764675406__s5bf3a4d02e2d4bea92404b3442f9ffb8"><h4 class="sectiontitle">Examples</h4><ul id="EN-US_TOPIC_0000001764675406__ul2957165112218"><li id="EN-US_TOPIC_0000001764675406__li169571751172213">Read the LakeFormation table using the external schema.<ul id="EN-US_TOPIC_0000001764675406__ul8883125116226"><li id="EN-US_TOPIC_0000001764675406__li68262371354">Create <strong id="EN-US_TOPIC_0000001764675406__b1626405213322">lf_server</strong>. The corresponding foreign data wrapper is <strong id="EN-US_TOPIC_0000001764675406__b17554456183217">DFS_FDW</strong>.<div class="note" id="EN-US_TOPIC_0000001764675406__note8826103711513"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001764675406__p1592725663711">For details about how to create <strong id="EN-US_TOPIC_0000001764675406__b149327312332">lf_server</strong>, see section "Managing LakeFormation Data Sources" in User Guide.</p>
</div></div>
</li><li id="EN-US_TOPIC_0000001764675406__li88270371251">Create an external schema, set <strong id="EN-US_TOPIC_0000001764675406__b145561203336">SOURCE</strong> to <strong id="EN-US_TOPIC_0000001764675406__b1613232510336">lakeformation</strong>, and set the DLI server associated with the table to <strong id="EN-US_TOPIC_0000001764675406__b1549562863319">lf_server</strong>. In the following command, <strong id="EN-US_TOPIC_0000001764675406__b42832018342">DATABASE</strong> is the LakeFormation database, and <strong id="EN-US_TOPIC_0000001764675406__b4993192243419">CATALOG</strong> is the LakeFormation catalog to be accessed. Replace them with the actual ones you use.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen185898566617"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">EXTERNAL</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">ex_lf</span>
<span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="k">SOURCE</span><span class="w"> </span><span class="n">lakeformation</span>
<span class="w"> </span><span class="k">DATABASE</span><span class="w"> </span><span class="s1">'demo'</span>
<span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">lf_server</span>
<span class="w"> </span><span class="k">CATALOG</span><span class="w"> </span><span class="s1">'hive'</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001764675406__li1644912651511">Role authorization<ul id="EN-US_TOPIC_0000001764675406__ul123951411172019"><li id="EN-US_TOPIC_0000001764675406__li12395141162013">Query the current user.</li><li id="EN-US_TOPIC_0000001764675406__li1994205172218">SELECT current_user;</li><li id="EN-US_TOPIC_0000001764675406__li596871913208">Create a role that matches the current role on the LakeFormation management plane and assign it the table access permissions.</li></ul>
</li><li id="EN-US_TOPIC_0000001764675406__li14827037457">Query data in the LakeFormation table using the external schema. <strong id="EN-US_TOPIC_0000001764675406__b67510173818">test_lf</strong> indicates the LakeFormation table to be accessed.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen108271237959"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="k">COUNT</span><span class="p">(</span><span class="o">*</span><span class="p">)</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">ex_dli</span><span class="p">.</span><span class="n">test_lf</span><span class="p">;</span>
<span class="w"> </span><span class="k">count</span><span class="w"> </span>
<span class="c1">-------</span>
<span class="w"> </span><span class="mi">20</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</li></ul>
</div>
<ul id="EN-US_TOPIC_0000001764675406__ul11181186233"><li id="EN-US_TOPIC_0000001764675406__li81182862314">Read a DLI multi-version foreign table using external schema. This function is supported only in 8.3.0 or later.<div class="note" id="EN-US_TOPIC_0000001764675406__note168081922195118"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001764675406__p7438183617387">DLI tables and DLI internal tables in Lakehouse mode can be accessed.</p>
</div></div>
<ul id="EN-US_TOPIC_0000001764675406__ul209944782313"><li id="EN-US_TOPIC_0000001764675406__li1418712359250">Create <strong id="EN-US_TOPIC_0000001764675406__b130300441131931">dli_server</strong>, with <strong id="EN-US_TOPIC_0000001764675406__b108158656131931">DFS_FDW</strong> as the foreign data wrapper.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen47651321910"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">dli_server</span><span class="w"> </span><span class="k">FOREIGN</span><span class="w"> </span><span class="k">DATA</span><span class="w"> </span><span class="n">WRAPPER</span><span class="w"> </span><span class="n">DFS_FDW</span><span class="w"> </span><span class="k">OPTIONS</span><span class="w"> </span><span class="p">(</span><span class="w"> </span>
<span class="w"> </span><span class="n">ADDRESS</span><span class="w"> </span><span class="s1">'obs.example.com'</span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">ACCESS_KEY</span><span class="w"> </span><span class="s1">'xxxxxxxxx'</span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">SECRET_ACCESS_KEY</span><span class="w"> </span><span class="s1">'yyyyyyyyyyyyy'</span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="k">TYPE</span><span class="w"> </span><span class="s1">'DLI'</span><span class="p">,</span>
<span class="w"> </span><span class="n">DLI_ADDRESS</span><span class="w"> </span><span class="s1">'dli.example.com'</span><span class="p">,</span>
<span class="w"> </span><span class="n">DLI_ACCESS_KEY</span><span class="w"> </span><span class="s1">'xxxxxxxxx'</span><span class="p">,</span>
<span class="w"> </span><span class="n">DLI_SECRET_ACCESS_KEY</span><span class="w"> </span><span class="s1">'yyyyyyyyyyyyy'</span>
<span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<div class="note" id="EN-US_TOPIC_0000001764675406__note8766183210918"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001764675406__ul176616321898"><li id="EN-US_TOPIC_0000001764675406__li35346467463"><strong id="EN-US_TOPIC_0000001764675406__b67409627731931">ADDRESS</strong> is the endpoint of OBS. <strong id="EN-US_TOPIC_0000001764675406__b176626390831931">DLI_ADDRESS</strong> is the endpoint of DLI. Replace it with the actual endpoint.</li><li id="EN-US_TOPIC_0000001764675406__li16766173215913"><strong id="EN-US_TOPIC_0000001764675406__b169406386831931">ACCESS_KEY</strong> and <strong id="EN-US_TOPIC_0000001764675406__b148776324231931">SECRET_ACCESS_KEY</strong> are access keys for the cloud account system to access OBS. Replace the values as needed.</li><li id="EN-US_TOPIC_0000001764675406__li132649461317"><strong id="EN-US_TOPIC_0000001764675406__b84481923031931">DLI_ACCESS_KEY</strong> and <strong id="EN-US_TOPIC_0000001764675406__b155422589031931">DLI_SECRET_ACCESS_KEY</strong> are access keys for the cloud account system to access DLI. Replace the values as needed.</li><li id="EN-US_TOPIC_0000001764675406__li9766832893"><strong id="EN-US_TOPIC_0000001764675406__b55275235031931">TYPE</strong> indicates the server type. Retain the value <strong id="EN-US_TOPIC_0000001764675406__b35399835331931">DLI</strong>.</li></ul>
</div></div>
</li><li id="EN-US_TOPIC_0000001764675406__li7554163017262">Create an external schema, set <strong id="EN-US_TOPIC_0000001764675406__b765019564393">SOURCE</strong> to <strong id="EN-US_TOPIC_0000001764675406__b1073015818394">dli</strong>, and set the DLI server associated with the table to <strong id="EN-US_TOPIC_0000001764675406__b131848484010">dli_server</strong>. <strong id="EN-US_TOPIC_0000001764675406__b223919144012">project_id</strong> is <em id="EN-US_TOPIC_0000001764675406__i1166916255409">xxxxxxxxxxxxxxx</em>, and <strong id="EN-US_TOPIC_0000001764675406__b20705733134018">database_name</strong> on DLI is <strong id="EN-US_TOPIC_0000001764675406__b174231038114016">database123</strong>. Replace them as needed.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen9131143442620"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="k">EXTERNAL</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">ex_dli</span><span class="w"> </span>
<span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="k">SOURCE</span><span class="w"> </span><span class="n">dli</span>
<span class="w"> </span><span class="k">DATABASE</span><span class="w"> </span><span class="s1">'database123'</span>
<span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">dli_server</span><span class="w"> </span>
<span class="w"> </span><span class="k">options</span><span class="w"> </span><span class="p">(</span><span class="n">dli_project_id</span><span class="w"> </span><span class="s1">'xxxxxxxxxxxxxxx'</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001764675406__li68870477225">Query data in the DLI multi-version table using the external schema. <strong id="EN-US_TOPIC_0000001764675406__b8272632114111">test_dli</strong> indicates the DLI table to be accessed. Replace it as needed.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen1076815328910"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="k">COUNT</span><span class="p">(</span><span class="o">*</span><span class="p">)</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">ex_dli</span><span class="p">.</span><span class="n">test_dli</span><span class="p">;</span>
<span class="w"> </span><span class="k">count</span><span class="w"> </span>
<span class="c1">-------</span>
<span class="w"> </span><span class="mi">20</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</li><li id="EN-US_TOPIC_0000001764675406__li20878175515121">Reads the <strong id="EN-US_TOPIC_0000001764675406__b1780153411311">hivemetastore</strong> table using the external schema. Only 9.1.0 and later versions support this function.<ul id="EN-US_TOPIC_0000001764675406__ul185981128132516"><li id="EN-US_TOPIC_0000001764675406__li76146261253">Create <strong id="EN-US_TOPIC_0000001764675406__b8467157112412">obs/hdfs server</strong>, with <strong id="EN-US_TOPIC_0000001764675406__b5467657182417">DFS_FDW</strong> as the foreign data wrapper.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen57071812363"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">CREATE</span><span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">hdfs_server</span><span class="w"> </span>
<span class="k">FOREIGN</span><span class="w"> </span><span class="k">DATA</span><span class="w"> </span><span class="n">WRAPPER</span><span class="w"> </span><span class="n">HDFS_FDW</span><span class="w"> </span>
<span class="k">OPTIONS</span><span class="w"> </span><span class="p">(</span>
<span class="n">address</span><span class="w"> </span><span class="s1">'***.***.***.***:9000'</span><span class="p">,</span><span class="w"> </span>
<span class="k">type</span><span class="s1">'HDFS'</span><span class="p">);</span>
<span class="k">CREATE</span><span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">obs_server</span><span class="w"> </span>
<span class="k">FOREIGN</span><span class="w"> </span><span class="k">DATA</span><span class="w"> </span><span class="n">WRAPPER</span><span class="w"> </span><span class="n">dfs_fdw</span><span class="w"> </span>
<span class="k">OPTIONS</span><span class="w"> </span><span class="p">(</span><span class="w"> </span>
<span class="w"> </span><span class="n">address</span><span class="w"> </span><span class="s1">'obs.example.com'</span><span class="w"> </span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">ACCESS_KEY</span><span class="w"> </span><span class="s1">'access_key_value_to_be_replaced'</span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">SECRET_ACCESS_KEY</span><span class="w"> </span><span class="s1">'secret_access_key_value_to_be_replaced'</span><span class="p">,</span><span class="w"> </span>
<span class="w"> </span><span class="n">encrypt</span><span class="w"> </span><span class="s1">'on'</span><span class="p">,</span>
<span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="s1">'obs'</span><span class="w"> </span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001764675406__li1217062112617">Create an external schema. Set <strong id="EN-US_TOPIC_0000001764675406__b169012044162518">SOURCE</strong> to <strong id="EN-US_TOPIC_0000001764675406__b59022449256">hive</strong> and the server associated with the table to <strong id="EN-US_TOPIC_0000001764675406__b69027449252">obs/hdfs server</strong>. <strong id="EN-US_TOPIC_0000001764675406__b19235197113415">DATABASE</strong> indicates the HMS database, <strong id="EN-US_TOPIC_0000001764675406__b1030711145348">METAADDRESS</strong> indicates the HiveMetaStore communication interface, and <strong id="EN-US_TOPIC_0000001764675406__b1317543913345">CONFIGURATION</strong> indicates the location where HiveMetaStore configuration files are saved. Adjust these parameters to meet your site's requirements.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen17197181412910"><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="k">CREATE</span><span class="w"> </span><span class="k">EXTERNAL</span><span class="w"> </span><span class="k">SCHEMA</span><span class="w"> </span><span class="n">ex_hms</span><span class="w"> </span>
<span class="w"> </span><span class="k">WITH</span><span class="w"> </span><span class="k">SOURCE</span><span class="w"> </span><span class="n">source_type</span>
<span class="w"> </span><span class="k">DATABASE</span><span class="w"> </span><span class="s1">'db_name'</span>
<span class="w"> </span><span class="n">SERVER</span><span class="w"> </span><span class="n">srv_name</span>
<span class="w"> </span><span class="n">METAADDRESS</span><span class="w"> </span><span class="s1">'address'</span>
<span class="w"> </span><span class="n">CONFIGURATION</span><span class="w"> </span><span class="s1">'confpath'</span><span class="p">;</span>
</pre></div></td></tr></table></div>
</div>
</li><li id="EN-US_TOPIC_0000001764675406__li44105535278">Queries data in the HMS table using the external schema. <strong id="EN-US_TOPIC_0000001764675406__b3466157143514">test_hms</strong> indicates the HMS table to be accessed. Replace it as needed.<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001764675406__screen891854819283"><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></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="k">COUNT</span><span class="p">(</span><span class="o">*</span><span class="p">)</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">ex_hms</span><span class="p">.</span><span class="n">test_hms</span><span class="p">;</span>
<span class="w"> </span><span class="k">count</span><span class="w"> </span>
<span class="c1">-------</span>
<span class="w"> </span><span class="mi">20</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</li></ul>
</li></ul>
<div class="section" id="EN-US_TOPIC_0000001764675406__sf5b9082b29dc4619be18df64147e273a"><h4 class="sectiontitle">Helpful Links</h4><p id="EN-US_TOPIC_0000001764675406__ab9d043f673ca47ea82b9e1b144d08686"><a href="dws_06_0366.html">ALTER EXTERNAL SCHEMA</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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