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doc-exports/docs/dws/dev/dws_04_1232.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_0000001885872897"></a><a name="EN-US_TOPIC_0000001885872897"></a>
<h1 class="topictitle1">PGXC_DISK_CACHE_STATS</h1>
<div id="body0000001885872897"><p id="EN-US_TOPIC_0000001885872897__p181160210116"><strong id="EN-US_TOPIC_0000001885872897__b16612171171911">PGXC_DISK_CACHE_STATS</strong> records the usage of file cache. This system view is supported only by clusters of version 9.1.0 or later.</p>
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="EN-US_TOPIC_0000001885872897__table26921257143119" frame="border" border="1" rules="all"><caption><b>Table 1 </b>PGXC_DISK_CACHE_STATS columns</caption><thead align="left"><tr id="EN-US_TOPIC_0000001885872897__row1169235723119"><th align="left" class="cellrowborder" valign="top" width="33.33333333333333%" id="mcps1.3.2.2.4.1.1"><p id="EN-US_TOPIC_0000001885872897__p1169319572319"><strong id="EN-US_TOPIC_0000001885872897__b15413240044383">Column</strong></p>
</th>
<th align="left" class="cellrowborder" valign="top" width="33.33333333333333%" id="mcps1.3.2.2.4.1.2"><p id="EN-US_TOPIC_0000001885872897__p1869305703114">Type</p>
</th>
<th align="left" class="cellrowborder" valign="top" width="33.33333333333333%" id="mcps1.3.2.2.4.1.3"><p id="EN-US_TOPIC_0000001885872897__p1469325713317">Description</p>
</th>
</tr>
</thead>
<tbody><tr id="EN-US_TOPIC_0000001885872897__row16933574315"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p1169313573311">node_name</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p46931757133117">Text</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p126931857163113">Node name.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row14693195743115"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p9693125717318">total_read</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p3693125753118">Bigint</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p26932057163116">Total number of accesses to disk cache.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row66937579315"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p8693145711310">local_read</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p1169325714317">Bigint</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p3693657143114">Total number of times disk cache reads from local disk.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row17693155719319"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p1369375714317">remote_read</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p36932575316">Bigint</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p13693145719314">Total number of times disk cache reads from remote storage.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row10693175743115"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p769325711318">hit_rate</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p66931557173113">numeric(5,2)</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p76934572317">Hit rate of disk cache.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row969320571317"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p18693205713113">cache_size</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p6693257153118">Bigint</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p18693205793114">Total size of data saved in disk cache, in KB.</p>
</td>
</tr>
<tr id="EN-US_TOPIC_0000001885872897__row869375783119"><td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.1 "><p id="EN-US_TOPIC_0000001885872897__p1069312571314">fill_rate</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.2 "><p id="EN-US_TOPIC_0000001885872897__p76937574311">numeric(5,2)</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="mcps1.3.2.2.4.1.3 "><p id="EN-US_TOPIC_0000001885872897__p1169355720319">Fill rate of disk cache.</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="EN-US_TOPIC_0000001885872897__section45581706481"><h4 class="sectiontitle">Example</h4><p id="EN-US_TOPIC_0000001885872897__p19300111317481">Query the hit rate of disk cache on each node.</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001885872897__screen174233518498"><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>
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<span class="normal"> 9</span>
<span class="normal">10</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">hit_rate</span><span class="w"> </span><span class="k">FROM</span><span class="w"> </span><span class="n">pgxc_disk_cache_stats</span><span class="p">;</span>
<span class="w"> </span><span class="n">hit_rate</span>
<span class="c1">----------</span>
<span class="w"> </span><span class="mi">56</span><span class="p">.</span><span class="mi">91</span>
<span class="w"> </span><span class="mi">56</span><span class="p">.</span><span class="mi">85</span>
<span class="w"> </span><span class="n">NaN</span>
<span class="w"> </span><span class="n">NaN</span>
<span class="w"> </span><span class="n">NaN</span>
<span class="w"> </span><span class="n">NaN</span>
<span class="p">(</span><span class="mi">6</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_0639.html">System Views</a></div>
</div>
</div>
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