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<!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>51.3. pg_am</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 V1.79.1" /><link rel="prev" href="catalog-pg-aggregate.html" title="51.2. pg_aggregate" /><link rel="next" href="catalog-pg-amop.html" title="51.4. pg_amop" /></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">51.3. <code xmlns="http://www.w3.org/1999/xhtml" class="structname">pg_am</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-aggregate.html" title="51.2. pg_aggregate">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 51. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 51. System Catalogs</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-amop.html" title="51.4. pg_amop">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="CATALOG-PG-AM"><div class="titlepage"><div><div><h2 class="title" style="clear: both">51.3. <code class="structname">pg_am</code></h2></div></div></div><a id="id-1.10.4.5.2" class="indexterm"></a><p>
   The catalog <code class="structname">pg_am</code> stores information about
   relation access methods.  There is one row for each access method supported
   by the system.
   Currently, only tables and indexes have access methods. The requirements for table
   and index access methods are discussed in detail in <a class="xref" href="tableam.html" title="Chapter 60. Table Access Method Interface Definition">Chapter 60</a> and
   <a class="xref" href="indexam.html" title="Chapter 61. Index Access Method Interface Definition">Chapter 61</a> respectively.
  </p><div class="table" id="id-1.10.4.5.4"><p class="title"><strong>Table 51.3. <code class="structname">pg_am</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_am 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</td></tr><tr><td><code class="structfield">amname</code></td><td><code class="type">name</code></td><td> </td><td>Name of the access method</td></tr><tr><td><code class="structfield">amhandler</code></td><td><code class="type">regproc</code></td><td><code class="literal"><a class="link" href="catalog-pg-proc.html" title="51.39. pg_proc"><code class="structname">pg_proc</code></a>.oid</code></td><td>
       OID of a handler function that is responsible for supplying information
       about the access method
      </td></tr><tr><td><code class="structfield">amtype</code></td><td><code class="type">char</code></td><td> </td><td>
       <code class="literal">t</code> = table (including materialized views),
       <code class="literal">i</code> = index.
      </td></tr></tbody></table></div></div><br class="table-break" /><div class="note"><h3 class="title">Note</h3><p>
    Before <span class="productname">PostgreSQL</span> 9.6, <code class="structname">pg_am</code>
    contained many additional columns representing properties of index access
    methods.  That data is now only directly visible at the C code level.
    However, <code class="function">pg_index_column_has_property()</code> and related
    functions have been added to allow SQL queries to inspect index access
    method properties; see <a class="xref" href="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE" title="Table 9.68. System Catalog Information Functions">Table 9.68</a>.
   </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalog-pg-aggregate.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-amop.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">51.2. <code class="structname">pg_aggregate</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 51.4. <code class="structname">pg_amop</code></td></tr></table></div></body></html>