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><H1
><A
NAME="SQL-ALTERINDEX"
></A
>ALTER INDEX</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN63813"
></A
><H2
>Name</H2
>ALTER INDEX -- change the definition of an index</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN63818"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>ALTER INDEX [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> RENAME TO <TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
>
ALTER INDEX [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> SET TABLESPACE <TT
CLASS="REPLACEABLE"
><I
>tablespace_name</I
></TT
>
ALTER INDEX [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> SET ( <TT
CLASS="REPLACEABLE"
><I
>storage_parameter</I
></TT
> = <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
> [, ... ] )
ALTER INDEX [ IF EXISTS ] <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> RESET ( <TT
CLASS="REPLACEABLE"
><I
>storage_parameter</I
></TT
> [, ... ] )</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN63829"
></A
><H2
>Description</H2
><P
> <TT
CLASS="COMMAND"
>ALTER INDEX</TT
> changes the definition of an existing index.
There are several subforms:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>RENAME</TT
></DT
><DD
><P
> The <TT
CLASS="LITERAL"
>RENAME</TT
> form changes the name of the index.
There is no effect on the stored data.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET TABLESPACE</TT
></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.
See also
<A
HREF="sql-createtablespace.html"
>CREATE TABLESPACE</A
>.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>SET ( <TT
CLASS="REPLACEABLE"
><I
>storage_parameter</I
></TT
> = <TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
> [, ... ] )</TT
></DT
><DD
><P
> This form changes one or more index-method-specific storage parameters
for the index. See
<A
HREF="sql-createindex.html"
>CREATE INDEX</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
HREF="sql-reindex.html"
>REINDEX</A
>
to get the desired effects.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>RESET ( <TT
CLASS="REPLACEABLE"
><I
>storage_parameter</I
></TT
> [, ... ] )</TT
></DT
><DD
><P
> This form resets one or more index-method-specific storage parameters to
their defaults. As with <TT
CLASS="LITERAL"
>SET</TT
>, a <TT
CLASS="LITERAL"
>REINDEX</TT
>
might be needed to update the index entirely.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN63863"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>IF EXISTS</TT
></DT
><DD
><P
> Do not throw an error if the index does not exist. A notice is issued
in this case.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></DT
><DD
><P
> The name (possibly schema-qualified) of an existing index to
alter.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>new_name</I
></TT
></DT
><DD
><P
> The new name for the index.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>tablespace_name</I
></TT
></DT
><DD
><P
> The tablespace to which the index will be moved.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>storage_parameter</I
></TT
></DT
><DD
><P
> The name of an index-method-specific storage parameter.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>value</I
></TT
></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"
><A
NAME="AEN63896"
></A
><H2
>Notes</H2
><P
> These operations are also possible using
<A
HREF="sql-altertable.html"
>ALTER TABLE</A
>.
<TT
CLASS="COMMAND"
>ALTER INDEX</TT
> is in fact just an alias for the forms
of <TT
CLASS="COMMAND"
>ALTER TABLE</TT
> that apply to indexes.
</P
><P
> There was formerly an <TT
CLASS="COMMAND"
>ALTER INDEX OWNER</TT
> 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"
><A
NAME="AEN63905"
></A
><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></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN63913"
></A
><H2
>Compatibility</H2
><P
> <TT
CLASS="COMMAND"
>ALTER INDEX</TT
> is a <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
extension.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN63918"
></A
><H2
>See Also</H2
><A
HREF="sql-createindex.html"
>CREATE INDEX</A
>, <A
HREF="sql-reindex.html"
>REINDEX</A
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