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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!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>52.90. pg_stats_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="view-pg-stats.html" title="52.89. pg_stats" /><link rel="next" href="view-pg-stats-ext-exprs.html" title="52.91. pg_stats_ext_exprs" /></head><body id="docContent" class="container-fluid col-10"><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">52.90. <code xmlns="http://www.w3.org/1999/xhtml" class="structname">pg_stats_ext</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="view-pg-stats.html" title="52.89. pg_stats">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 14.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="view-pg-stats-ext-exprs.html" title="52.91. pg_stats_ext_exprs">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="VIEW-PG-STATS-EXT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">52.90. <code class="structname">pg_stats_ext</code></h2></div></div></div><a id="id-1.10.4.92.2" class="indexterm"></a><p>
The view <code class="structname">pg_stats_ext</code> provides access to
information about each extended statistics object in the database,
combining information stored in the <a class="link" href="catalog-pg-statistic-ext.html" title="52.50. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a>
and <a class="link" href="catalog-pg-statistic-ext-data.html" title="52.51. pg_statistic_ext_data"><code class="structname">pg_statistic_ext_data</code></a>
catalogs. This view allows access only to rows of
<a class="link" href="catalog-pg-statistic-ext.html" title="52.50. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a> and <a class="link" href="catalog-pg-statistic-ext-data.html" title="52.51. pg_statistic_ext_data"><code class="structname">pg_statistic_ext_data</code></a>
that correspond to tables the user has permission to read, and therefore
it is safe to allow public read access to this view.
</p><p>
<code class="structname">pg_stats_ext</code> is also designed to present the
information in a more readable format than the underlying catalogs
— at the cost that its schema must be extended whenever new types
of extended statistics are added to <a class="link" href="catalog-pg-statistic-ext.html" title="52.50. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a>.
</p><div class="table" id="id-1.10.4.92.5"><p class="title"><strong>Table 52.91. <code class="structname">pg_stats_ext</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_stats_ext Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
Column Type
</p>
<p>
Description
</p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">schemaname</code> <code class="type">name</code>
(references <a class="link" href="catalog-pg-namespace.html" title="52.32. pg_namespace"><code class="structname">pg_namespace</code></a>.<code class="structfield">nspname</code>)
</p>
<p>
Name of schema containing table
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">tablename</code> <code class="type">name</code>
(references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">relname</code>)
</p>
<p>
Name of table
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">statistics_schemaname</code> <code class="type">name</code>
(references <a class="link" href="catalog-pg-namespace.html" title="52.32. pg_namespace"><code class="structname">pg_namespace</code></a>.<code class="structfield">nspname</code>)
</p>
<p>
Name of schema containing extended statistics object
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">statistics_name</code> <code class="type">name</code>
(references <a class="link" href="catalog-pg-statistic-ext.html" title="52.50. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a>.<code class="structfield">stxname</code>)
</p>
<p>
Name of extended statistics object
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">statistics_owner</code> <code class="type">name</code>
(references <a class="link" href="catalog-pg-authid.html" title="52.8. pg_authid"><code class="structname">pg_authid</code></a>.<code class="structfield">rolname</code>)
</p>
<p>
Owner of the extended statistics object
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">attnames</code> <code class="type">name[]</code>
(references <a class="link" href="catalog-pg-attribute.html" title="52.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attname</code>)
</p>
<p>
Names of the columns included in the extended statistics object
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">exprs</code> <code class="type">text[]</code>
</p>
<p>
Expressions included in the extended statistics object
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">kinds</code> <code class="type">char[]</code>
</p>
<p>
Types of extended statistics object enabled for this record
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">n_distinct</code> <code class="type">pg_ndistinct</code>
</p>
<p>
N-distinct counts for combinations of column values. If greater
than zero, the estimated number of distinct values in the combination.
If less than zero, the negative of the number of distinct values divided
by the number of rows.
(The negated form is used when <code class="command">ANALYZE</code> believes that
the number of distinct values is likely to increase as the table grows;
the positive form is used when the column seems to have a fixed number
of possible values.) For example, -1 indicates a unique combination of
columns in which the number of distinct combinations is the same as the
number of rows.
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">dependencies</code> <code class="type">pg_dependencies</code>
</p>
<p>
Functional dependency statistics
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">most_common_vals</code> <code class="type">text[]</code>
</p>
<p>
A list of the most common combinations of values in the columns.
(Null if no combinations seem to be more common than any others.)
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">most_common_val_nulls</code> <code class="type">bool[]</code>
</p>
<p>
A list of NULL flags for the most common combinations of values.
(Null when <code class="structfield">most_common_vals</code> is.)
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">most_common_freqs</code> <code class="type">float8[]</code>
</p>
<p>
A list of the frequencies of the most common combinations,
i.e., number of occurrences of each divided by total number of rows.
(Null when <code class="structfield">most_common_vals</code> is.)
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">most_common_base_freqs</code> <code class="type">float8[]</code>
</p>
<p>
A list of the base frequencies of the most common combinations,
i.e., product of per-value frequencies.
(Null when <code class="structfield">most_common_vals</code> is.)
</p></td></tr></tbody></table></div></div><br class="table-break" /><p>
The maximum number of entries in the array fields can be controlled on a
column-by-column basis using the <a class="link" href="sql-altertable.html" title="ALTER TABLE"><code class="command">ALTER
TABLE SET STATISTICS</code></a> command, or globally by setting the
<a class="xref" href="runtime-config-query.html#GUC-DEFAULT-STATISTICS-TARGET">default_statistics_target</a> run-time parameter.
</p></div><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navfooter"><hr></hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="view-pg-stats.html" title="52.89. pg_stats">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="view-pg-stats-ext-exprs.html" title="52.91. pg_stats_ext_exprs">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.89. <code xmlns="http://www.w3.org/1999/xhtml" class="structname">pg_stats</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 14.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 52.91. <code xmlns="http://www.w3.org/1999/xhtml" class="structname">pg_stats_ext_exprs</code></td></tr></table></div></body></html>
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