Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
author: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-13 13:44:03 +0000
committer: Daniel Baumann <daniel.baumann@progress-linux.org> 2024-04-13 13:44:03 +0000
commit: 293913568e6a7a86fd1479e1cff8e2ecb58d6568 (patch)
tree: fc3b469a3ec5ab71b36ea97cc7aaddb838423a0c /doc/src/sgml/html/view-pg-stats-ext-exprs.html
parent: Initial commit. (diff)
download: postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.tar.xz
postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.zip
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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>54.29. pg_stats_ext_exprs</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-ext.html" title="54.28. pg_stats_ext" /><link rel="next" href="view-pg-tables.html" title="54.30. pg_tables" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">54.29. <code class="structname">pg_stats_ext_exprs</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="view-pg-stats-ext.html" title="54.28. pg_stats_ext">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="views.html" title="Chapter 54. System Views">Up</a></td><th width="60%" align="center">Chapter 54. System Views</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="view-pg-tables.html" title="54.30. pg_tables">Next</a></td></tr></table><hr /></div><div class="sect1" id="VIEW-PG-STATS-EXT-EXPRS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">54.29. <code class="structname">pg_stats_ext_exprs</code> <a href="#VIEW-PG-STATS-EXT-EXPRS" class="id_link">#</a></h2></div></div></div><a id="id-1.10.5.33.2" class="indexterm"></a><p>
+   The view <code class="structname">pg_stats_ext_exprs</code> provides access to
+   information about all expressions included in extended statistics objects,
+   combining information stored in the <a class="link" href="catalog-pg-statistic-ext.html" title="53.52. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a>
+   and <a class="link" href="catalog-pg-statistic-ext-data.html" title="53.53. 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="53.52. pg_statistic_ext"><code class="structname">pg_statistic_ext</code></a> and <a class="link" href="catalog-pg-statistic-ext-data.html" title="53.53. 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_exprs</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 the structure
+   of statistics in <code class="structname">pg_statistic_ext</code> changes.
+  </p><div class="table" id="id-1.10.5.33.5"><p class="title"><strong>Table 54.29. <code class="structname">pg_stats_ext_exprs</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_stats_ext_exprs 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="53.32. 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="53.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">relname</code>)
+      </p>
+      <p>
+       Name of table the statistics object is defined on
+      </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="53.32. 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="53.52. 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="53.8. 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">expr</code> <code class="type">text</code>
+      </p>
+      <p>
+       Expression included in the extended statistics object
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">inherited</code> <code class="type">bool</code>
+       (references <a class="link" href="catalog-pg-statistic-ext-data.html" title="53.53. pg_statistic_ext_data"><code class="structname">pg_statistic_ext_data</code></a>.<code class="structfield">stxdinherit</code>)
+      </p>
+      <p>
+       If true, the stats include values from child tables, not just the
+       values in the specified relation
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">null_frac</code> <code class="type">float4</code>
+      </p>
+      <p>
+       Fraction of expression entries that are null
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">avg_width</code> <code class="type">int4</code>
+      </p>
+      <p>
+       Average width in bytes of expression's entries
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">n_distinct</code> <code class="type">float4</code>
+      </p>
+      <p>
+       If greater than zero, the estimated number of distinct values in the
+       expression.  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 expression seems to have a fixed number of possible values.)  For
+       example, -1 indicates a unique expression in which the number of distinct
+       values is the same as the number of rows.
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">most_common_vals</code> <code class="type">anyarray</code>
+      </p>
+      <p>
+       A list of the most common values in the expression. (Null if
+       no values 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_freqs</code> <code class="type">float4[]</code>
+      </p>
+      <p>
+       A list of the frequencies of the most common values,
+       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">histogram_bounds</code> <code class="type">anyarray</code>
+      </p>
+      <p>
+       A list of values that divide the expression's values into groups of
+       approximately equal population.  The values in
+       <code class="structfield">most_common_vals</code>, if present, are omitted from this
+       histogram calculation.  (This expression is null if the expression data type
+       does not have a <code class="literal">&lt;</code> operator or if the
+       <code class="structfield">most_common_vals</code> list accounts for the entire
+       population.)
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">correlation</code> <code class="type">float4</code>
+      </p>
+      <p>
+       Statistical correlation between physical row ordering and
+       logical ordering of the expression values.  This ranges from -1 to +1.
+       When the value is near -1 or +1, an index scan on the expression will
+       be estimated to be cheaper than when it is near zero, due to reduction
+       of random access to the disk.  (This expression is null if the expression's
+       data type does not have a <code class="literal">&lt;</code> operator.)
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">most_common_elems</code> <code class="type">anyarray</code>
+      </p>
+      <p>
+       A list of non-null element values most often appearing within values of
+       the expression. (Null for scalar types.)
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">most_common_elem_freqs</code> <code class="type">float4[]</code>
+      </p>
+      <p>
+       A list of the frequencies of the most common element values, i.e., the
+       fraction of rows containing at least one instance of the given value.
+       Two or three additional values follow the per-element frequencies;
+       these are the minimum and maximum of the preceding per-element
+       frequencies, and optionally the frequency of null elements.
+       (Null when <code class="structfield">most_common_elems</code> is.)
+      </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
+       <code class="structfield">elem_count_histogram</code> <code class="type">float4[]</code>
+      </p>
+      <p>
+       A histogram of the counts of distinct non-null element values within the
+       values of the expression, followed by the average number of distinct
+       non-null elements.  (Null for scalar types.)
+      </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 class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="view-pg-stats-ext.html" title="54.28. pg_stats_ext">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="views.html" title="Chapter 54. System Views">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="view-pg-tables.html" title="54.30. pg_tables">Next</a></td></tr><tr><td width="40%" align="left" valign="top">54.28. <code class="structname">pg_stats_ext</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 54.30. <code class="structname">pg_tables</code></td></tr></table></div></body></html>
+\ No newline at end of file
author	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-13 13:44:03 +0000
committer	Daniel Baumann <daniel.baumann@progress-linux.org>	2024-04-13 13:44:03 +0000
commit	293913568e6a7a86fd1479e1cff8e2ecb58d6568 (patch)
tree	fc3b469a3ec5ab71b36ea97cc7aaddb838423a0c /doc/src/sgml/html/view-pg-stats-ext-exprs.html
parent	Initial commit. (diff)
download	postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.tar.xz postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.zip