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   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>52.52. pg_statistic_ext</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="catalog-pg-statistic.html" title="52.51. pg_statistic" /><link rel="next" href="catalog-pg-statistic-ext-data.html" title="52.53. pg_statistic_ext_data" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">52.52. <code class="structname">pg_statistic_ext</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-statistic.html" title="52.51. pg_statistic">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 52. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 52. System Catalogs</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-statistic-ext-data.html" title="52.53. pg_statistic_ext_data">Next</a></td></tr></table><hr /></div><div class="sect1" id="CATALOG-PG-STATISTIC-EXT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">52.52. <code class="structname">pg_statistic_ext</code> <a href="#CATALOG-PG-STATISTIC-EXT" class="id_link">#</a></h2></div></div></div><a id="id-1.10.4.54.2" class="indexterm"></a><p>
   3    The catalog <code class="structname">pg_statistic_ext</code>
   4    holds definitions of extended planner statistics.
   5    Each row in this catalog corresponds to a <em class="firstterm">statistics object</em>
   6    created with <a class="link" href="sql-createstatistics.html" title="CREATE STATISTICS"><code class="command">CREATE STATISTICS</code></a>.
   7   </p><div class="table" id="id-1.10.4.54.4"><p class="title"><strong>Table 52.52. <code class="structname">pg_statistic_ext</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_statistic_ext Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
   8        Column Type
   9       </p>
  10       <p>
  11        Description
  12       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
  13        <code class="structfield">oid</code> <code class="type">oid</code>
  14       </p>
  15       <p>
  16        Row identifier
  17       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  18        <code class="structfield">stxrelid</code> <code class="type">oid</code>
  19        (references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)
  20       </p>
  21       <p>
  22        Table containing the columns described by this object
  23       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  24        <code class="structfield">stxname</code> <code class="type">name</code>
  25       </p>
  26       <p>
  27        Name of the statistics object
  28       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  29        <code class="structfield">stxnamespace</code> <code class="type">oid</code>
  30        (references <a class="link" href="catalog-pg-namespace.html" title="52.32. pg_namespace"><code class="structname">pg_namespace</code></a>.<code class="structfield">oid</code>)
  31       </p>
  32       <p>
  33        The OID of the namespace that contains this statistics object
  34       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  35        <code class="structfield">stxowner</code> <code class="type">oid</code>
  36        (references <a class="link" href="catalog-pg-authid.html" title="52.8. pg_authid"><code class="structname">pg_authid</code></a>.<code class="structfield">oid</code>)
  37       </p>
  38       <p>
  39        Owner of the statistics object
  40       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  41        <code class="structfield">stxkeys</code> <code class="type">int2vector</code>
  42        (references <a class="link" href="catalog-pg-attribute.html" title="52.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)
  43       </p>
  44       <p>
  45        An array of attribute numbers, indicating which table columns are
  46        covered by this statistics object;
  47        for example a value of <code class="literal">1 3</code> would
  48        mean that the first and the third table columns are covered
  49       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  50        <code class="structfield">stxstattarget</code> <code class="type">int2</code>
  51       </p>
  52       <p>
  53        <code class="structfield">stxstattarget</code> controls the level of detail
  54        of statistics accumulated for this statistics object by
  55        <a class="link" href="sql-analyze.html" title="ANALYZE"><code class="command">ANALYZE</code></a>.
  56        A zero value indicates that no statistics should be collected.
  57        A null value says to use the maximum of the statistics targets of
  58        the referenced columns, if set, or the system default statistics target.
  59        Positive values of <code class="structfield">stxstattarget</code>
  60        determine the target number of <span class="quote">“<span class="quote">most common values</span>”</span>
  61        to collect.
  62       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  63        <code class="structfield">stxkind</code> <code class="type">char[]</code>
  64       </p>
  65       <p>
  66        An array containing codes for the enabled statistics kinds;
  67        valid values are:
  68        <code class="literal">d</code> for n-distinct statistics,
  69        <code class="literal">f</code> for functional dependency statistics,
  70        <code class="literal">m</code> for most common values (MCV) list statistics, and
  71        <code class="literal">e</code> for expression statistics
  72       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  73        <code class="structfield">stxexprs</code> <code class="type">pg_node_tree</code>
  74       </p>
  75       <p>
  76        Expression trees (in <code class="function">nodeToString()</code>
  77        representation) for statistics object attributes that are not simple
  78        column references.  This is a list with one element per expression.
  79        Null if all statistics object attributes are simple references.
  80       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
  81    The <code class="structname">pg_statistic_ext</code> entry is filled in
  82    completely during <a class="link" href="sql-createstatistics.html" title="CREATE STATISTICS"><code class="command">CREATE STATISTICS</code></a>, but the actual
  83    statistical values are not computed then.
  84    Subsequent <a class="link" href="sql-analyze.html" title="ANALYZE"><code class="command">ANALYZE</code></a> commands compute the desired values
  85    and populate an entry in the
  86    <a class="link" href="catalog-pg-statistic-ext-data.html" title="52.53. pg_statistic_ext_data"><code class="structname">pg_statistic_ext_data</code></a>
  87    catalog.
  88   </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalog-pg-statistic.html" title="52.51. pg_statistic">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 52. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-statistic-ext-data.html" title="52.53. pg_statistic_ext_data">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.51. <code class="structname">pg_statistic</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 52.53. <code class="structname">pg_statistic_ext_data</code></td></tr></table></div></body></html>