linkend="sql-reindex"><command>REINDEX</command></link>
to get the desired effects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESET ( <replaceable class="parameter">storage_parameter</replaceable> [, ... ] )</literal></term>
<listitem>
<para>
This form resets one or more index-method-specific storage parameters to
their defaults. As with <literal>SET</literal>, a <literal>REINDEX</literal>
might be needed to update the index entirely.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ALTER [ COLUMN ] <replaceable class="parameter">column_number</replaceable> SET STATISTICS <replaceable class="parameter">integer</replaceable></literal></term>
<listitem>
<para>
This form sets the per-column statistics-gathering target for
subsequent <link linkend="sql-analyze"><command>ANALYZE</command></link> 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 (<xref linkend="guc-default-statistics-target"/>).
For more information on the use of statistics by the
<productname>PostgreSQL</productname> query planner, refer to
<xref linkend="planner-stats"/>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF EXISTS</literal></term>
<listitem>
<para>
Do not throw an error if the index does not exist. A notice is issued
in this case.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">column_number</replaceable></term>
<listitem>
<para>
The ordinal number refers to the ordinal (left-to-right) position
of the index column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (possibly schema-qualified) of an existing index to
alter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_name</replaceable></term>
<listitem>
<para>
The new name for the index.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">tablespace_name</replaceable></term>
<listitem>
<para>