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diff --git a/doc/src/sgml/html/sql-alterindex.html b/doc/src/sgml/html/sql-alterindex.html new file mode 100644 index 0000000..fb1d3ef --- /dev/null +++ b/doc/src/sgml/html/sql-alterindex.html @@ -0,0 +1,138 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!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>ALTER 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-altergroup.html" title="ALTER GROUP" /><link rel="next" href="sql-alterlanguage.html" title="ALTER 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">ALTER INDEX</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-altergroup.html" title="ALTER 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 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-alterlanguage.html" title="ALTER LANGUAGE">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-ALTERINDEX"><div class="titlepage"></div><a id="id-1.9.3.16.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">ALTER INDEX</span></h2><p>ALTER INDEX — change the definition of an index</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis"> +ALTER INDEX [ IF EXISTS ] <em class="replaceable"><code>name</code></em> RENAME TO <em class="replaceable"><code>new_name</code></em> +ALTER INDEX [ IF EXISTS ] <em class="replaceable"><code>name</code></em> SET TABLESPACE <em class="replaceable"><code>tablespace_name</code></em> +ALTER INDEX <em class="replaceable"><code>name</code></em> ATTACH PARTITION <em class="replaceable"><code>index_name</code></em> +ALTER INDEX <em class="replaceable"><code>name</code></em> [ NO ] DEPENDS ON EXTENSION <em class="replaceable"><code>extension_name</code></em> +ALTER INDEX [ IF EXISTS ] <em class="replaceable"><code>name</code></em> SET ( <em class="replaceable"><code>storage_parameter</code></em> [= <em class="replaceable"><code>value</code></em>] [, ... ] ) +ALTER INDEX [ IF EXISTS ] <em class="replaceable"><code>name</code></em> RESET ( <em class="replaceable"><code>storage_parameter</code></em> [, ... ] ) +ALTER INDEX [ IF EXISTS ] <em class="replaceable"><code>name</code></em> ALTER [ COLUMN ] <em class="replaceable"><code>column_number</code></em> + SET STATISTICS <em class="replaceable"><code>integer</code></em> +ALTER INDEX ALL IN TABLESPACE <em class="replaceable"><code>name</code></em> [ OWNED BY <em class="replaceable"><code>role_name</code></em> [, ... ] ] + SET TABLESPACE <em class="replaceable"><code>new_tablespace</code></em> [ NOWAIT ] +</pre></div><div class="refsect1" id="id-1.9.3.16.5"><h2>Description</h2><p> + <code class="command">ALTER INDEX</code> changes the definition of an existing index. + There are several subforms described below. Note that the lock level required + may differ for each subform. An <code class="literal">ACCESS EXCLUSIVE</code> lock is held + unless explicitly noted. When multiple subcommands are listed, the lock + held will be the strictest one required from any subcommand. + + </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">RENAME</code></span></dt><dd><p> + The <code class="literal">RENAME</code> form changes the name of the index. + If the index is associated with a table constraint (either + <code class="literal">UNIQUE</code>, <code class="literal">PRIMARY KEY</code>, + or <code class="literal">EXCLUDE</code>), the constraint is renamed as well. + There is no effect on the stored data. + </p><p> + Renaming an index acquires a <code class="literal">SHARE UPDATE EXCLUSIVE</code> + lock. + </p></dd><dt><span class="term"><code class="literal">SET TABLESPACE</code></span></dt><dd><p> + This form changes the index's tablespace to the specified tablespace and + moves the data file(s) associated with the index to the new tablespace. + To change the tablespace of an index, you must own the index and have + <code class="literal">CREATE</code> privilege on the new tablespace. + All indexes in the current database in a tablespace can be moved by using + the <code class="literal">ALL IN TABLESPACE</code> form, which will lock all + indexes to be moved and then move each one. This form also supports + <code class="literal">OWNED BY</code>, which will only move indexes owned by the + roles specified. If the <code class="literal">NOWAIT</code> option is specified + then the command will fail if it is unable to acquire all of the locks + required immediately. Note that system catalogs will not be moved by + this command, use <code class="command">ALTER DATABASE</code> or explicit + <code class="command">ALTER INDEX</code> invocations instead if desired. + See also + <a class="link" href="sql-createtablespace.html" title="CREATE TABLESPACE"><code class="command">CREATE TABLESPACE</code></a>. + </p></dd><dt><span class="term"><code class="literal">ATTACH PARTITION</code></span></dt><dd><p> + Causes the named index to become attached to the altered index. + The named index must be on a partition of the table containing the + index being altered, and have an equivalent definition. An attached + index cannot be dropped by itself, and will automatically be dropped + if its parent index is dropped. + </p></dd><dt><span class="term"><code class="literal">DEPENDS ON EXTENSION <em class="replaceable"><code>extension_name</code></em></code><br /></span><span class="term"><code class="literal">NO DEPENDS ON EXTENSION <em class="replaceable"><code>extension_name</code></em></code></span></dt><dd><p> + This form marks the index as dependent on the extension, or no longer + dependent on that extension if <code class="literal">NO</code> is specified. + An index that's marked as dependent on an extension is automatically + dropped when the extension is dropped. + </p></dd><dt><span class="term"><code class="literal">SET ( <em class="replaceable"><code>storage_parameter</code></em> [= <em class="replaceable"><code>value</code></em>] [, ... ] )</code></span></dt><dd><p> + This form changes one or more index-method-specific storage parameters + for the index. See + <a class="link" href="sql-createindex.html" title="CREATE INDEX"><code class="command">CREATE INDEX</code></a> + for details on the available parameters. Note that the index contents + will not be modified immediately by this command; depending on the + parameter you might need to rebuild the index with + <a class="link" href="sql-reindex.html" title="REINDEX"><code class="command">REINDEX</code></a> + to get the desired effects. + </p></dd><dt><span class="term"><code class="literal">RESET ( <em class="replaceable"><code>storage_parameter</code></em> [, ... ] )</code></span></dt><dd><p> + This form resets one or more index-method-specific storage parameters to + their defaults. As with <code class="literal">SET</code>, a <code class="literal">REINDEX</code> + might be needed to update the index entirely. + </p></dd><dt><span class="term"><code class="literal">ALTER [ COLUMN ] <em class="replaceable"><code>column_number</code></em> SET STATISTICS <em class="replaceable"><code>integer</code></em></code></span></dt><dd><p> + This form sets the per-column statistics-gathering target for + subsequent <a class="link" href="sql-analyze.html" title="ANALYZE"><code class="command">ANALYZE</code></a> operations, though can + be used only on index columns that are defined as an expression. + Since expressions lack a unique name, we refer to them using the + ordinal number of the index column. + The target can be set in the range 0 to 10000; alternatively, set it + to -1 to revert to using the system default statistics + target (<a class="xref" href="runtime-config-query.html#GUC-DEFAULT-STATISTICS-TARGET">default_statistics_target</a>). + For more information on the use of statistics by the + <span class="productname">PostgreSQL</span> query planner, refer to + <a class="xref" href="planner-stats.html" title="14.2. Statistics Used by the Planner">Section 14.2</a>. + </p></dd></dl></div><p> + </p></div><div class="refsect1" id="id-1.9.3.16.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">IF EXISTS</code></span></dt><dd><p> + Do not throw an error if the index does not exist. A notice is issued + in this case. + </p></dd><dt><span class="term"><em class="replaceable"><code>column_number</code></em></span></dt><dd><p> + The ordinal number refers to the ordinal (left-to-right) position + of the index column. + </p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p> + The name (possibly schema-qualified) of an existing index to + alter. + </p></dd><dt><span class="term"><em class="replaceable"><code>new_name</code></em></span></dt><dd><p> + The new name for the index. + </p></dd><dt><span class="term"><em class="replaceable"><code>tablespace_name</code></em></span></dt><dd><p> + The tablespace to which the index will be moved. + </p></dd><dt><span class="term"><em class="replaceable"><code>extension_name</code></em></span></dt><dd><p> + The name of the extension that the index is to depend on. + </p></dd><dt><span class="term"><em class="replaceable"><code>storage_parameter</code></em></span></dt><dd><p> + The name of an index-method-specific storage parameter. + </p></dd><dt><span class="term"><em class="replaceable"><code>value</code></em></span></dt><dd><p> + The new value for an index-method-specific storage parameter. + This might be a number or a word depending on the parameter. + </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.16.7"><h2>Notes</h2><p> + These operations are also possible using + <a class="link" href="sql-altertable.html" title="ALTER TABLE"><code class="command">ALTER TABLE</code></a>. + <code class="command">ALTER INDEX</code> is in fact just an alias for the forms + of <code class="command">ALTER TABLE</code> that apply to indexes. + </p><p> + There was formerly an <code class="command">ALTER INDEX OWNER</code> variant, but + this is now ignored (with a warning). An index cannot have an owner + different from its table's owner. Changing the table's owner + automatically changes the index as well. + </p><p> + Changing any part of a system catalog index is not permitted. + </p></div><div class="refsect1" id="id-1.9.3.16.8"><h2>Examples</h2><p> + To rename an existing index: +</p><pre class="programlisting"> +ALTER INDEX distributors RENAME TO suppliers; +</pre><p> + </p><p> + To move an index to a different tablespace: +</p><pre class="programlisting"> +ALTER INDEX distributors SET TABLESPACE fasttablespace; +</pre><p> + </p><p> + To change an index's fill factor (assuming that the index method + supports it): +</p><pre class="programlisting"> +ALTER INDEX distributors SET (fillfactor = 75); +REINDEX INDEX distributors; +</pre><p> + Set the statistics-gathering target for an expression index: +</p><pre class="programlisting"> +CREATE INDEX coord_idx ON measured (x, y, (z + t)); +ALTER INDEX coord_idx ALTER COLUMN 3 SET STATISTICS 1000; +</pre></div><div class="refsect1" id="id-1.9.3.16.9"><h2>Compatibility</h2><p> + <code class="command">ALTER INDEX</code> is a <span class="productname">PostgreSQL</span> + extension. + </p></div><div class="refsect1" id="id-1.9.3.16.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-createindex.html" title="CREATE INDEX"><span class="refentrytitle">CREATE INDEX</span></a>, <a class="xref" href="sql-reindex.html" title="REINDEX"><span class="refentrytitle">REINDEX</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-altergroup.html" title="ALTER 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-alterlanguage.html" title="ALTER LANGUAGE">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ALTER GROUP </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> ALTER LANGUAGE</td></tr></table></div></body></html>
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