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Lu, Huayi ef0ada5a59 DWS DEV 20240716 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>
2024-11-02 09:07:47 +00:00

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<a name="EN-US_TOPIC_0000001510283433"></a><a name="EN-US_TOPIC_0000001510283433"></a>
<h1 class="topictitle1">Hybrid Data Warehouse Functions</h1>
<div id="body0000001490854057"><div class="section" id="EN-US_TOPIC_0000001510283433__section111833513559"><h4 class="sectiontitle">hstore_light_merge(rel_name text)</h4><p id="EN-US_TOPIC_0000001510283433__p1570053018110">Description: This function is used to manually perform lightweight cleanup on HStore tables and holds the level-3 lock of the target table.</p>
<p id="EN-US_TOPIC_0000001510283433__p136441319310">Return type: int</p>
<p id="EN-US_TOPIC_0000001510283433__p1868611814316">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001510283433__s6f2a8091f7c749d2b4794a0c2b847f25"><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">SELECT</span><span class="w"> </span><span class="n">hstore_light_merge</span><span class="p">(</span><span class="s1">'reason_select'</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510283433__section299316461039"><h4 class="sectiontitle">hstore_full_merge(rel_name text)</h4><p id="EN-US_TOPIC_0000001510283433__p29931946036">Description: This function is used to manually perform full cleanup on HStore tables.</p>
<p id="EN-US_TOPIC_0000001510283433__p299334617312">Return type: int</p>
<div class="notice" id="EN-US_TOPIC_0000001510283433__note7302124416519"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><ul id="EN-US_TOPIC_0000001510283433__ul57954194615"><li id="EN-US_TOPIC_0000001510283433__li187955144617">This operation forcibly merges all the visible operations of the delta table to the primary table, and then creates an empty delta table. During this period, this operation holds the level-8 lock of the table.</li><li id="EN-US_TOPIC_0000001510283433__li12795101164615">The duration of this operation depends on the amount of data in the delta table. You must enable the HStore clearing thread to ensure unnecessary data in the HStore table is cleared in a timely manner.</li></ul>
</div></div>
<p id="EN-US_TOPIC_0000001510283433__p1699310461333">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001510283433__screen89931546336"><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">SELECT</span><span class="w"> </span><span class="n">hstore_full_merge</span><span class="p">(</span><span class="s1">'reason_select'</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510283433__section143989322016"><h4 class="sectiontitle">pgxc_get_small_cu_info(rel_name text, row_count int)</h4><p id="EN-US_TOPIC_0000001510283433__p33985321901">Description: Obtains the small CU information of the target table. The second parameter <strong id="EN-US_TOPIC_0000001510283433__b7133172819512">row_count</strong> is optional and indicates the small CU threshold. If the number of live tuples in a CU is fewer than the threshold, the CU is considered as a small CU. The default value is <strong id="EN-US_TOPIC_0000001510283433__b04531314869">200</strong>. This function is supported only by clusters of version 8.2.1.300 or later.</p>
<p id="EN-US_TOPIC_0000001510283433__p53986325017"><strong id="EN-US_TOPIC_0000001510283433__b124741053192">Return type</strong>: record</p>
<p id="EN-US_TOPIC_0000001510283433__p439843217013">Return value:</p>
<p id="EN-US_TOPIC_0000001510283433__p103986321907"><strong id="EN-US_TOPIC_0000001510283433__b827090938104127">node_name</strong>: DN name.</p>
<p id="EN-US_TOPIC_0000001510283433__p1539815321011"><strong id="EN-US_TOPIC_0000001510283433__b662734912914">part_name</strong>: partition name. This column is empty for non-partitioned tables.</p>
<p id="EN-US_TOPIC_0000001510283433__p93989321012"><strong id="EN-US_TOPIC_0000001510283433__b2704792105">zero_cu_count</strong>: number of 0 CUs. If all data in a CU is deleted, the CU is called 0 CU.</p>
<p id="EN-US_TOPIC_0000001510283433__p69321828463"><strong id="EN-US_TOPIC_0000001510283433__b124891129181013">small_cu_count</strong>: number of small CUs. When a CU has live data that is less than the threshold, the CU is called a small CU.</p>
<p id="EN-US_TOPIC_0000001510283433__p102294351167"><strong id="EN-US_TOPIC_0000001510283433__b1190158161111">total_cu_count</strong>: total number of CUs.</p>
<p id="EN-US_TOPIC_0000001510283433__p865235841018">It should be noted that a CU may contain multiple columns.</p>
<p id="EN-US_TOPIC_0000001510283433__p1139883210017">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001510283433__screen15398432002"><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">SELECT</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">pgxc_get_small_cu_info</span><span class="p">(</span><span class="s1">'hs'</span><span class="p">);</span>
<span class="w"> </span><span class="n">node_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">part_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">zero_cu_count</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">small_cu_count</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">total_cu_count</span>
<span class="c1">-----------+-----------+---------------+----------------+----------------</span>
<span class="w"> </span><span class="n">dn_1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">1</span>
<span class="w"> </span><span class="n">dn_2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</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">2</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510283433__section1337433919496"><h4 class="sectiontitle">gs_hstore_compaction(rel_name text, row_count int)</h4><p id="EN-US_TOPIC_0000001510283433__p143461423494">Description: Merges small CUs of the target table. The second parameter <strong id="EN-US_TOPIC_0000001510283433__b18299131316129">row_count</strong> is optional and indicates the small CU threshold. If the number of live tuples in a CU is fewer than the threshold, the CU is considered as a small CU. The default value is <strong id="EN-US_TOPIC_0000001510283433__b133001313171216">100</strong>. This function is supported only by 8.2.1.300 and later versions.</p>
<p id="EN-US_TOPIC_0000001510283433__p17259115844910">Return type: int</p>
<p id="EN-US_TOPIC_0000001510283433__p892305213492"><strong id="EN-US_TOPIC_0000001510283433__b183441336181216">Return value</strong>: <strong id="EN-US_TOPIC_0000001510283433__b102213394123">numCompactCU</strong>, which indicates the number of small CUs to be merged.</p>
</div>
<div class="note" id="EN-US_TOPIC_0000001510283433__note6798142175910"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="EN-US_TOPIC_0000001510283433__ul11722156509"><li id="EN-US_TOPIC_0000001510283433__li1172326208">A CU may contain multiple columns.</li><li id="EN-US_TOPIC_0000001510283433__li1172316002">The partition name cannot be input in the function. Currently, a single partition cannot be specified in this function.</li></ul>
</div></div>
<p id="EN-US_TOPIC_0000001510283433__p13991257175614">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001510283433__screen725501312587"><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">select</span><span class="w"> </span><span class="n">gs_hstore_compaction</span><span class="p">(</span><span class="s1">'hs'</span><span class="p">,</span><span class="w"> </span><span class="mi">10</span><span class="p">);</span>
</pre></div></td></tr></table></div>
</div>
<div class="section" id="EN-US_TOPIC_0000001510283433__section983914383316"><h4 class="sectiontitle">pgxc_get_hstore_delta_info(rel_name text)</h4><p id="EN-US_TOPIC_0000001510283433__p13839134393315">Description: This function is used to obtain the delta table information of the target table, including the delta table size and the number of <strong id="EN-US_TOPIC_0000001510283433__b15279663323">INSERT</strong>, <strong id="EN-US_TOPIC_0000001510283433__b1384688322">DELETE</strong>, and <strong id="EN-US_TOPIC_0000001510283433__b13890898326">UPDATE </strong>records. This function is supported only by clusters of version 8.2.1.100 or later.</p>
<p id="EN-US_TOPIC_0000001510283433__p2083954363315">Return type: record</p>
<p id="EN-US_TOPIC_0000001510283433__p252285805817">Return value:</p>
<p id="EN-US_TOPIC_0000001510283433__p94796317591"><strong id="EN-US_TOPIC_0000001510283433__b1690432520330">node_name</strong>: DN name.</p>
<p id="EN-US_TOPIC_0000001510283433__p87271619135910"><strong id="EN-US_TOPIC_0000001510283433__b8345030183313">part_name</strong>: partition name. This column is set to <strong id="EN-US_TOPIC_0000001510283433__b16320195203219">non-partition table</strong> if the table is not a partitioned table.</p>
<p id="EN-US_TOPIC_0000001510283433__p9257145115916"><strong id="EN-US_TOPIC_0000001510283433__b1266863416416">live_tup</strong>: number of live tuples.</p>
<p id="EN-US_TOPIC_0000001510283433__p18878921204"><strong id="EN-US_TOPIC_0000001510283433__b112681650387">n_i_type</strong>: number of records whose type is <strong id="EN-US_TOPIC_0000001510283433__b32683514385">i</strong> (insert). An <strong id="EN-US_TOPIC_0000001510283433__b848915603318">i</strong> record indicates one insertion, which can be single insertion or batch insertion.</p>
<p id="EN-US_TOPIC_0000001510283433__p2588311015"><strong id="EN-US_TOPIC_0000001510283433__b7163810383">n_d_type</strong>: number of records whose type is <strong id="EN-US_TOPIC_0000001510283433__b10168815389">d</strong> (delete). One <strong id="EN-US_TOPIC_0000001510283433__b1868061115342">d</strong> record indicates one deletion, which can be single deletion or batch deletion.</p>
<p id="EN-US_TOPIC_0000001510283433__p16581146208"><strong id="EN-US_TOPIC_0000001510283433__b1551317103387">n_x_type</strong>: number of records whose type is <strong id="EN-US_TOPIC_0000001510283433__b105143100383">x</strong> (deletions generated by update).</p>
<p id="EN-US_TOPIC_0000001510283433__p1262461111"><strong id="EN-US_TOPIC_0000001510283433__b692121210389">n_u_type</strong>: number of records whose type is <strong id="EN-US_TOPIC_0000001510283433__b169211124380">u</strong> (lightweight update).</p>
<p id="EN-US_TOPIC_0000001510283433__p157421122410"><strong id="EN-US_TOPIC_0000001510283433__b985321511381">n_m_type</strong>: number of records whose type is <strong id="EN-US_TOPIC_0000001510283433__b1785316159385">m</strong> (merge).</p>
<p id="EN-US_TOPIC_0000001510283433__p875013713110"><strong id="EN-US_TOPIC_0000001510283433__b750513421365">data_size</strong>: table size.</p>
<p id="EN-US_TOPIC_0000001510283433__p883974393319">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001510283433__screen983914434336"><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">SELECT</span><span class="w"> </span><span class="o">*</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">pgxc_get_hstore_delta_info</span><span class="p">(</span><span class="s1">'hs_part'</span><span class="p">);</span>
<span class="w"> </span><span class="n">node_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">part_name</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">live_tup</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">n_i_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">n_d_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">n_x_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">n_u_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">n_m_type</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">data_size</span>
<span class="c1">-----------+-----------+----------+----------+----------+----------+----------+----------+-----------</span>
<span class="w"> </span><span class="n">dn_1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">p1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">8192</span>
<span class="w"> </span><span class="n">dn_1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">p2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">8192</span>
<span class="w"> </span><span class="n">dn_1</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="n">p3</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">2</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="o">|</span><span class="w"> </span><span class="mi">8192</span>
<span class="p">(</span><span class="mi">3</span><span class="w"> </span><span class="k">rows</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_1023.html">Hybrid Data Warehouse</a></div>
</div>
</div>
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