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   2 <!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>52.3. 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 Vsnapshot" /><link rel="prev" href="catalog-pg-aggregate.html" title="52.2. pg_aggregate" /><link rel="next" href="catalog-pg-amop.html" title="52.4. pg_amop" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">52.3. <code class="structname">pg_am</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-aggregate.html" title="52.2. pg_aggregate">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 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-amop.html" title="52.4. pg_amop">Next</a></td></tr></table><hr /></div><div class="sect1" id="CATALOG-PG-AM"><div class="titlepage"><div><div><h2 class="title" style="clear: both">52.3. <code class="structname">pg_am</code> <a href="#CATALOG-PG-AM" class="id_link">#</a></h2></div></div></div><a id="id-1.10.4.5.2" class="indexterm"></a><p>
   3    The catalog <code class="structname">pg_am</code> stores information about
   4    relation access methods.  There is one row for each access method supported
   5    by the system.
   6    Currently, only tables and indexes have access methods. The requirements for table
   7    and index access methods are discussed in detail in <a class="xref" href="tableam.html" title="Chapter 62. Table Access Method Interface Definition">Chapter 62</a> and
   8    <a class="xref" href="indexam.html" title="Chapter 63. Index Access Method Interface Definition">Chapter 63</a> respectively.
   9   </p><div class="table" id="id-1.10.4.5.4"><p class="title"><strong>Table 52.3. <code class="structname">pg_am</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_am Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
  10        Column Type
  11       </p>
  12       <p>
  13        Description
  14       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
  15        <code class="structfield">oid</code> <code class="type">oid</code>
  16       </p>
  17       <p>
  18        Row identifier
  19       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  20        <code class="structfield">amname</code> <code class="type">name</code>
  21       </p>
  22       <p>
  23        Name of the access method
  24       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  25        <code class="structfield">amhandler</code> <code class="type">regproc</code>
  26        (references <a class="link" href="catalog-pg-proc.html" title="52.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)
  27       </p>
  28       <p>
  29        OID of a handler function that is responsible for supplying information
  30        about the access method
  31       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  32        <code class="structfield">amtype</code> <code class="type">char</code>
  33       </p>
  34       <p>
  35        <code class="literal">t</code> = table (including materialized views),
  36        <code class="literal">i</code> = index.
  37       </p></td></tr></tbody></table></div></div><br class="table-break" /><div class="note"><h3 class="title">Note</h3><p>
  38     Before <span class="productname">PostgreSQL</span> 9.6, <code class="structname">pg_am</code>
  39     contained many additional columns representing properties of index access
  40     methods.  That data is now only directly visible at the C code level.
  41     However, <code class="function">pg_index_column_has_property()</code> and related
  42     functions have been added to allow SQL queries to inspect index access
  43     method properties; see <a class="xref" href="functions-info.html#FUNCTIONS-INFO-CATALOG-TABLE" title="Table 9.76. System Catalog Information Functions">Table 9.76</a>.
  44    </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" title="52.2. pg_aggregate">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="catalog-pg-amop.html" title="52.4. pg_amop">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.2. <code class="structname">pg_aggregate</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 52.4. <code class="structname">pg_amop</code></td></tr></table></div></body></html>