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Lu, Huayi a24ca60074 DWS DEVELOPER 811 version 
Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
2023-01-19 13:37:49 +00:00

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<a name="EN-US_TOPIC_0000001145694391"></a><a name="EN-US_TOPIC_0000001145694391"></a>
<h1 class="topictitle1">PGXC_GET_TABLE_SKEWNESS</h1>
<div id="body1547169602820"><p id="EN-US_TOPIC_0000001145694391__p8060118"><strong id="EN-US_TOPIC_0000001145694391__b13464201255510">PGXC_GET_TABLE_SKEWNESS</strong> displays the data skew on tables in the current database.</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="EN-US_TOPIC_0000001145694391__t6c300cc1797847adae05b4bd400a30a9" frame="border" border="1" rules="all"><caption><b>Table 1 </b>PGXC_GET_TABLE_SKEWNESS columns</caption><thead align="left"><tr id="EN-US_TOPIC_0000001145694391__r7c9f4b37cd894ed68dcbd282fd2464a1"><th align="left" class="cellrowborder" valign="top" width="33.33%" id="mcps1.3.2.2.4.1.1"><p id="EN-US_TOPIC_0000001145694391__a17658ed8d76e4514bec9f53c7f992505">Name</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="20.919999999999998%" id="mcps1.3.2.2.4.1.2"><p id="EN-US_TOPIC_0000001145694391__ac476c6793bc34253a8535512e32e902d">Type</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="45.75%" id="mcps1.3.2.2.4.1.3"><p id="EN-US_TOPIC_0000001145694391__aaf4f7de306a645a58a3cf2237d05fefc">Description</p>
</th>
</tr>
</thead>
<tbody><tr id="EN-US_TOPIC_0000001145694391__r30f39bf2a2f8419c9e110e6a9144636f"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p1160011111301">schemaname</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__a80f401d929a4440cbbd3ad959e86ef5f">name</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__a31b6bede08c24ade99acf8080ea89a00">Schema name of a table</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__r85f9c397e38641619053419ca445986c"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p155841225203011">tablename</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__a8fbd877be523468ba5ee8aead5954c13">name</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__a9f18b3b16ed64428a6b3edf483791408">Name of a table</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row1596942488"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p897184184816">totalsize</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p89817484814">numeric</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p1099145484">Total size of a table, in bytes</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__r3623c123596d4a31b27c3553584057e6"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p1219664054117">avgsize</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__ae7c6dd96828a454a817cc57962c15202">numeric(1000,0)</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__a576dc3a6fb874538a99a995c4c1534b0">Average table size (total table size divided by the number of DNs), which is the ideal size of tables distributed on each DN</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row204781949282"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p194796491814">maxratio</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p3479124915820">numeric(4,3)</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p204793499820">Ratio of the maximum table size on a single DN to the total table size</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row4302327154218"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p14386104410421">minratio</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p173030279421">numeric(4,3)</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p74751749105714">Ratio of the minimum table size on a single DN to the total table size</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row174687374424"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p04691337114217">skewsize</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p20469133724219">bigint</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p872812665817">Table skew rate (the maximum table size on a single DN minus the minimum table size on a single DN)</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row157104984219"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p16874914210">skewratio</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p179134915423">numeric(4,3)</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p199174924217">Table skew rate (skew size divided by total table size)</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001145694391__row14389195612816"><td class="cellrowborder" valign="top" width="33.33%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001145694391__p1118111812436">skewstddev</p>
</td>
<td class="cellrowborder" valign="top" width="20.919999999999998%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001145694391__p1636555125610">numeric(1000,0)</p>
</td>
<td class="cellrowborder" valign="top" width="45.75%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001145694391__p14390856089">Standard deviation of table distribution (For two tables of the same size, a larger deviation indicates a more severe skew.)</p>
</td>
</tr>
</tbody>
</table>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0639.html">System Views</a></div>
</div>
</div>
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