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Lu, Huayi 95132e24fc DWS UMN 830.201_new version 
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com>
Reviewed-by: Rechenburg, Matthias <matthias.rechenburg@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2024-05-27 11:54:34 +00:00

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<a name="EN-US_TOPIC_0000001387203636"></a><a name="EN-US_TOPIC_0000001387203636"></a>
<h1 class="topictitle1">How Do I Check Whether a Table Is Row-Stored or Column-Stored?</h1>
<div id="body0000001387203636"><p id="EN-US_TOPIC_0000001387203636__p085914245531">The storage mode of a table is controlled by the <span id="EN-US_TOPIC_0000001387203636__ph8388186122">ORIENTATION</span> parameter in the table creation statement. <strong id="EN-US_TOPIC_0000001387203636__b66607235451">row</strong> indicates row storage, and <strong id="EN-US_TOPIC_0000001387203636__b2088412944512">column</strong> indicates column storage.</p>
<p id="EN-US_TOPIC_0000001387203636__p1892955411391"></p>
<p id="EN-US_TOPIC_0000001387203636__p1238133013617">You can use the table definition function <strong id="EN-US_TOPIC_0000001387203636__b39931619183414">PG_GET_TABLEDEF</strong> to check whether the created table is row-store or column-store.</p>
<p id="EN-US_TOPIC_0000001387203636__p1250216010563">For example, <strong id="EN-US_TOPIC_0000001387203636__b8589334133414">orientation=column</strong> indicates a column-store table.</p>
<p id="EN-US_TOPIC_0000001387203636__p1721422125120">Currently, you cannot run the <strong id="EN-US_TOPIC_0000001387203636__b16497114514342">ALTER TABLE</strong> statement to modify the parameter <strong id="EN-US_TOPIC_0000001387203636__b17220165023419">ORIENTATION</strong>.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001387203636__screen113661430144618"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
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<span class="normal">14</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">PG_GET_TABLEDEF</span><span class="p">(</span><span class="s1">'customer_t1'</span><span class="p">);</span>
<span class="w"> </span><span class="n">pg_get_tabledef</span><span class="w"> </span>
<span class="c1">-----------------------------------------------------------------------------------</span>
<span class="w"> </span><span class="k">SET</span><span class="w"> </span><span class="n">search_path</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">tpchobs</span><span class="p">;</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="k">CREATE</span><span class="w"> </span><span class="k">TABLE</span><span class="w"> </span><span class="n">customer_t1</span><span class="w"> </span><span class="p">(</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="n">c_customer_sk</span><span class="w"> </span><span class="nb">integer</span><span class="p">,</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="n">c_customer_id</span><span class="w"> </span><span class="nb">character</span><span class="p">(</span><span class="mi">5</span><span class="p">),</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="n">c_first_name</span><span class="w"> </span><span class="nb">character</span><span class="p">(</span><span class="mi">6</span><span class="p">),</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="n">c_last_name</span><span class="w"> </span><span class="nb">character</span><span class="p">(</span><span class="mi">8</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="o">+</span>
<span class="w"> </span><span class="k">WITH</span><span class="w"> </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="w"> </span><span class="n">compression</span><span class="o">=</span><span class="n">middle</span><span class="p">,</span><span class="w"> </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="w"> </span><span class="n">enable_delta</span><span class="o">=</span><span class="k">false</span><span class="p">)</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="n">HASH</span><span class="p">(</span><span class="n">c_last_name</span><span class="p">)</span><span class="w"> </span><span class="o">+</span>
<span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="k">GROUP</span><span class="w"> </span><span class="n">group_version1</span><span class="p">;</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>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_03_0065.html">Database Usage</a></div>
</div>
</div>
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