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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>53.3. 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="53.2. pg_aggregate" /><link rel="next" href="catalog-pg-amop.html" title="53.4. 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">53.3. <code class="structname">pg_am</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-aggregate.html" title="53.2. pg_aggregate">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 53. System Catalogs</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.6 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-amop.html" title="53.4. 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">53.3. <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 63. Table Access Method Interface Definition">Chapter 63</a> and
<a class="xref" href="indexam.html" title="Chapter 64. Index Access Method Interface Definition">Chapter 64</a> respectively.
</p><div class="table" id="id-1.10.4.5.4"><p class="title"><strong>Table 53.3. <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">
Column Type
</p>
<p>
Description
</p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">oid</code> <code class="type">oid</code>
</p>
<p>
Row identifier
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">amname</code> <code class="type">name</code>
</p>
<p>
Name of the access method
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">amhandler</code> <code class="type">regproc</code>
(references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)
</p>
<p>
OID of a handler function that is responsible for supplying information
about the access method
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">amtype</code> <code class="type">char</code>
</p>
<p>
<code class="literal">t</code> = table (including materialized views),
<code class="literal">i</code> = index.
</p></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 9.71. System Catalog Information Functions">Table 9.71</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" title="53.2. pg_aggregate">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-amop.html" title="53.4. pg_amop">Next</a></td></tr><tr><td width="40%" align="left" valign="top">53.2. <code class="structname">pg_aggregate</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.6 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 53.4. <code class="structname">pg_amop</code></td></tr></table></div></body></html>
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