<?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>52.20. pg_enum</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-description.html" title="52.19. pg_description" /><link rel="next" href="catalog-pg-event-trigger.html" title="52.21. pg_event_trigger" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">52.20. <code xmlns="http://www.w3.org/1999/xhtml" class="structname">pg_enum</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-description.html" title="52.19. pg_description">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 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-event-trigger.html" title="52.21. pg_event_trigger">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="CATALOG-PG-ENUM"><div class="titlepage"><div><div><h2 class="title" style="clear: both">52.20. <code class="structname">pg_enum</code></h2></div></div></div><a id="id-1.10.4.22.2" class="indexterm"></a><p> The <code class="structname">pg_enum</code> catalog contains entries showing the values and labels for each enum type. The internal representation of a given enum value is actually the OID of its associated row in <code class="structname">pg_enum</code>. </p><div class="table" id="id-1.10.4.22.4"><p class="title"><strong>Table 52.20. <code class="structname">pg_enum</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_enum Columns" border="1"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th>Name</th><th>Type</th><th>References</th><th>Description</th></tr></thead><tbody><tr><td><code class="structfield">oid</code></td><td><code class="type">oid</code></td><td> </td><td>Row identifier (hidden attribute; must be explicitly selected)</td></tr><tr><td><code class="structfield">enumtypid</code></td><td><code class="type">oid</code></td><td><code class="literal"><a class="link" href="catalog-pg-type.html" title="52.62. pg_type"><code class="structname">pg_type</code></a>.oid</code></td><td>The OID of the <code class="structname">pg_type</code> entry owning this enum value</td></tr><tr><td><code class="structfield">enumsortorder</code></td><td><code class="type">float4</code></td><td> </td><td>The sort position of this enum value within its enum type</td></tr><tr><td><code class="structfield">enumlabel</code></td><td><code class="type">name</code></td><td> </td><td>The textual label for this enum value</td></tr></tbody></table></div></div><br class="table-break" /><p> The OIDs for <code class="structname">pg_enum</code> rows follow a special rule: even-numbered OIDs are guaranteed to be ordered in the same way as the sort ordering of their enum type. That is, if two even OIDs belong to the same enum type, the smaller OID must have the smaller <code class="structfield">enumsortorder</code> value. Odd-numbered OID values need bear no relationship to the sort order. This rule allows the enum comparison routines to avoid catalog lookups in many common cases. The routines that create and alter enum types attempt to assign even OIDs to enum values whenever possible. </p><p> When an enum type is created, its members are assigned sort-order positions 1..<em class="replaceable"><code>n</code></em>. But members added later might be given negative or fractional values of <code class="structfield">enumsortorder</code>. The only requirement on these values is that they be correctly ordered and unique within each enum type. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalog-pg-description.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-event-trigger.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.19. <code class="structname">pg_description</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 52.21. <code class="structname">pg_event_trigger</code></td></tr></table></div></body></html>
