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diff --git a/doc/src/sgml/html/view-pg-stats-ext-exprs.html b/doc/src/sgml/html/view-pg-stats-ext-exprs.html new file mode 100644 index 0000000..9b281a7 --- /dev/null +++ b/doc/src/sgml/html/view-pg-stats-ext-exprs.html @@ -0,0 +1,147 @@ +<?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 15.5 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></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"><</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"><</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 15.5 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>
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