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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&nbsp;--&nbsp;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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