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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>REINDEX</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-refreshmaterializedview.html" title="REFRESH MATERIALIZED VIEW" /><link rel="next" href="sql-release-savepoint.html" title="RELEASE SAVEPOINT" /></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">REINDEX</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-refreshmaterializedview.html" title="REFRESH MATERIALIZED VIEW">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 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-release-savepoint.html" title="RELEASE SAVEPOINT">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-REINDEX"><div class="titlepage"></div><a id="id-1.9.3.162.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">REINDEX</span></h2><p>REINDEX — rebuild indexes</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
REINDEX [ ( VERBOSE ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } <em class="replaceable"><code>name</code></em>
</pre></div><div class="refsect1" id="id-1.9.3.162.5"><h2>Description</h2><p>
<code class="command">REINDEX</code> rebuilds an index using the data
stored in the index's table, replacing the old copy of the index. There are
several scenarios in which to use <code class="command">REINDEX</code>:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
An index has become corrupted, and no longer contains valid
data. Although in theory this should never happen, in
practice indexes can become corrupted due to software bugs or
hardware failures. <code class="command">REINDEX</code> provides a
recovery method.
</p></li><li class="listitem"><p>
An index has become <span class="quote">“<span class="quote">bloated</span>”</span>, that is it contains many
empty or nearly-empty pages. This can occur with B-tree indexes in
<span class="productname">PostgreSQL</span> under certain uncommon access
patterns. <code class="command">REINDEX</code> provides a way to reduce
the space consumption of the index by writing a new version of
the index without the dead pages. See <a class="xref" href="routine-reindex.html" title="24.2. Routine Reindexing">Section 24.2</a> for more information.
</p></li><li class="listitem"><p>
You have altered a storage parameter (such as fillfactor)
for an index, and wish to ensure that the change has taken full effect.
</p></li><li class="listitem"><p>
An index build with the <code class="literal">CONCURRENTLY</code> option failed, leaving
an <span class="quote">“<span class="quote">invalid</span>”</span> index. Such indexes are useless but it can be
convenient to use <code class="command">REINDEX</code> to rebuild them. Note that
<code class="command">REINDEX</code> will not perform a concurrent build. To build the
index without interfering with production you should drop the index and
reissue the <code class="command">CREATE INDEX CONCURRENTLY</code> command.
</p></li></ul></div></div><div class="refsect1" id="id-1.9.3.162.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">INDEX</code></span></dt><dd><p>
Recreate the specified index.
</p></dd><dt><span class="term"><code class="literal">TABLE</code></span></dt><dd><p>
Recreate all indexes of the specified table. If the table has a
secondary <span class="quote">“<span class="quote">TOAST</span>”</span> table, that is reindexed as well.
</p></dd><dt><span class="term"><code class="literal">SCHEMA</code></span></dt><dd><p>
Recreate all indexes of the specified schema. If a table of this
schema has a secondary <span class="quote">“<span class="quote">TOAST</span>”</span> table, that is reindexed as
well. Indexes on shared system catalogs are also processed.
This form of <code class="command">REINDEX</code> cannot be executed inside a
transaction block.
</p></dd><dt><span class="term"><code class="literal">DATABASE</code></span></dt><dd><p>
Recreate all indexes within the current database.
Indexes on shared system catalogs are also processed.
This form of <code class="command">REINDEX</code> cannot be executed inside a
transaction block.
</p></dd><dt><span class="term"><code class="literal">SYSTEM</code></span></dt><dd><p>
Recreate all indexes on system catalogs within the current database.
Indexes on shared system catalogs are included.
Indexes on user tables are not processed.
This form of <code class="command">REINDEX</code> cannot be executed inside a
transaction block.
</p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
The name of the specific index, table, or database to be
reindexed. Index and table names can be schema-qualified.
Presently, <code class="command">REINDEX DATABASE</code> and <code class="command">REINDEX SYSTEM</code>
can only reindex the current database, so their parameter must match
the current database's name.
</p></dd><dt><span class="term"><code class="literal">VERBOSE</code></span></dt><dd><p>
Prints a progress report as each index is reindexed.
</p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.162.7"><h2>Notes</h2><p>
If you suspect corruption of an index on a user table, you can
simply rebuild that index, or all indexes on the table, using
<code class="command">REINDEX INDEX</code> or <code class="command">REINDEX TABLE</code>.
</p><p>
Things are more difficult if you need to recover from corruption of
an index on a system table. In this case it's important for the
system to not have used any of the suspect indexes itself.
(Indeed, in this sort of scenario you might find that server
processes are crashing immediately at start-up, due to reliance on
the corrupted indexes.) To recover safely, the server must be started
with the <code class="option">-P</code> option, which prevents it from using
indexes for system catalog lookups.
</p><p>
One way to do this is to shut down the server and start a single-user
<span class="productname">PostgreSQL</span> server
with the <code class="option">-P</code> option included on its command line.
Then, <code class="command">REINDEX DATABASE</code>, <code class="command">REINDEX SYSTEM</code>,
<code class="command">REINDEX TABLE</code>, or <code class="command">REINDEX INDEX</code> can be
issued, depending on how much you want to reconstruct. If in
doubt, use <code class="command">REINDEX SYSTEM</code> to select
reconstruction of all system indexes in the database. Then quit
the single-user server session and restart the regular server.
See the <a class="xref" href="app-postgres.html" title="postgres"><span class="refentrytitle"><span class="application">postgres</span></span></a> reference page for more
information about how to interact with the single-user server
interface.
</p><p>
Alternatively, a regular server session can be started with
<code class="option">-P</code> included in its command line options.
The method for doing this varies across clients, but in all
<span class="application">libpq</span>-based clients, it is possible to set
the <code class="envar">PGOPTIONS</code> environment variable to <code class="literal">-P</code>
before starting the client. Note that while this method does not
require locking out other clients, it might still be wise to prevent
other users from connecting to the damaged database until repairs
have been completed.
</p><p>
<code class="command">REINDEX</code> is similar to a drop and recreate of the index
in that the index contents are rebuilt from scratch. However, the locking
considerations are rather different. <code class="command">REINDEX</code> locks out writes
but not reads of the index's parent table. It also takes an exclusive lock
on the specific index being processed, which will block reads that attempt
to use that index. In contrast, <code class="command">DROP INDEX</code> momentarily takes
an exclusive lock on the parent table, blocking both writes and reads. The
subsequent <code class="command">CREATE INDEX</code> locks out writes but not reads; since
the index is not there, no read will attempt to use it, meaning that there
will be no blocking but reads might be forced into expensive sequential
scans.
</p><p>
Reindexing a single index or table requires being the owner of that
index or table. Reindexing a schema or database requires being the
owner of that schema or database. Note that is therefore sometimes
possible for non-superusers to rebuild indexes of tables owned by
other users. However, as a special exception, when
<code class="command">REINDEX DATABASE</code>, <code class="command">REINDEX SCHEMA</code>
or <code class="command">REINDEX SYSTEM</code> is issued by a non-superuser,
indexes on shared catalogs will be skipped unless the user owns the
catalog (which typically won't be the case). Of course, superusers
can always reindex anything.
</p><p>
Reindexing partitioned tables or partitioned indexes is not supported.
Each individual partition can be reindexed separately instead.
</p></div><div class="refsect1" id="id-1.9.3.162.8"><h2>Examples</h2><p>
Rebuild a single index:
</p><pre class="programlisting">
REINDEX INDEX my_index;
</pre><p>
</p><p>
Rebuild all the indexes on the table <code class="literal">my_table</code>:
</p><pre class="programlisting">
REINDEX TABLE my_table;
</pre><p>
</p><p>
Rebuild all indexes in a particular database, without trusting the
system indexes to be valid already:
</p><pre class="programlisting">
$ <strong class="userinput"><code>export PGOPTIONS="-P"</code></strong>
$ <strong class="userinput"><code>psql broken_db</code></strong>
...
broken_db=> REINDEX DATABASE broken_db;
broken_db=> \q
</pre></div><div class="refsect1" id="id-1.9.3.162.9"><h2>Compatibility</h2><p>
There is no <code class="command">REINDEX</code> command in the SQL standard.
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