begriffs open source - ai-pg/blob - full-docs/src/sgml/html/sql-dropindex.html

   1 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
   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>DROP INDEX</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="sql-dropgroup.html" title="DROP GROUP" /><link rel="next" href="sql-droplanguage.html" title="DROP LANGUAGE" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">DROP INDEX</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-dropgroup.html" title="DROP GROUP">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</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="sql-droplanguage.html" title="DROP LANGUAGE">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-DROPINDEX"><div class="titlepage"></div><a id="id-1.9.3.116.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">DROP INDEX</span></h2><p>DROP INDEX — remove an index</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
   3 DROP INDEX [ CONCURRENTLY ] [ IF EXISTS ] <em class="replaceable"><code>name</code></em> [, ...] [ CASCADE | RESTRICT ]
   4 </pre></div><div class="refsect1" id="id-1.9.3.116.5"><h2>Description</h2><p>
   5    <code class="command">DROP INDEX</code> drops an existing index from the database
   6    system. To execute this command you must be the owner of
   7    the index.
   8   </p></div><div class="refsect1" id="id-1.9.3.116.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">CONCURRENTLY</code></span></dt><dd><p>
   9       Drop the index without locking out concurrent selects, inserts, updates,
  10       and deletes on the index's table.  A normal <code class="command">DROP INDEX</code>
  11       acquires an <code class="literal">ACCESS EXCLUSIVE</code> lock on the table,
  12       blocking other accesses until the index drop can be completed.  With
  13       this option, the command instead waits until conflicting transactions
  14       have completed.
  15      </p><p>
  16       There are several caveats to be aware of when using this option.
  17       Only one index name can be specified, and the <code class="literal">CASCADE</code> option
  18       is not supported.  (Thus, an index that supports a <code class="literal">UNIQUE</code> or
  19       <code class="literal">PRIMARY KEY</code> constraint cannot be dropped this way.)
  20       Also, regular <code class="command">DROP INDEX</code> commands can be
  21       performed within a transaction block, but
  22       <code class="command">DROP INDEX CONCURRENTLY</code> cannot.
  23       Lastly, indexes on partitioned tables cannot be dropped using this
  24       option.
  25      </p><p>
  26       For temporary tables, <code class="command">DROP INDEX</code> is always
  27       non-concurrent, as no other session can access them, and
  28       non-concurrent index drop is cheaper.
  29      </p></dd><dt><span class="term"><code class="literal">IF EXISTS</code></span></dt><dd><p>
  30       Do not throw an error if the index does not exist. A notice is issued
  31       in this case.
  32      </p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
  33       The name (optionally schema-qualified) of an index to remove.
  34      </p></dd><dt><span class="term"><code class="literal">CASCADE</code></span></dt><dd><p>
  35       Automatically drop objects that depend on the index,
  36       and in turn all objects that depend on those objects
  37       (see <a class="xref" href="ddl-depend.html" title="5.15. Dependency Tracking">Section 5.15</a>).
  38      </p></dd><dt><span class="term"><code class="literal">RESTRICT</code></span></dt><dd><p>
  39       Refuse to drop the index if any objects depend on it.  This is
  40       the default.
  41      </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.116.7"><h2>Examples</h2><p>
  42    This command will remove the index <code class="literal">title_idx</code>:
  43
  44 </p><pre class="programlisting">
  45 DROP INDEX title_idx;
  46 </pre></div><div class="refsect1" id="id-1.9.3.116.8"><h2>Compatibility</h2><p>
  47    <code class="command">DROP INDEX</code> is a
  48    <span class="productname">PostgreSQL</span> language extension.  There
  49    are no provisions for indexes in the SQL standard.
  50   </p></div><div class="refsect1" id="id-1.9.3.116.9"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-createindex.html" title="CREATE INDEX"><span class="refentrytitle">CREATE INDEX</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-dropgroup.html" title="DROP GROUP">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-droplanguage.html" title="DROP LANGUAGE">Next</a></td></tr><tr><td width="40%" align="left" valign="top">DROP GROUP </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"> DROP LANGUAGE</td></tr></table></div></body></html>