</table>

<para>

GiST indexesrequire seven support functions,with an optional eighth, as

shown in <xref linkend="xindex-gist-support-table">.

GiST indexeshave nine support functions,two of which are optional,

asshown in <xref linkend="xindex-gist-support-table">.

(For more information see <xref linkend="GiST">.)

</para>

<entry>determine distance from key to query value (optional)</entry>

<entry>8</entry>

</row>

<row>

<entry><function>fetch</></entry>

<entry>compute original representation of a compressed key for

index-only scans (optional)</entry>

<entry>9</entry>

</row>

</tbody>

</tgroup>

</table>

</table>

<para>

GIN indexesrequire four support functions,with an optional fifth, as

shown in <xref linkend="xindex-gin-support-table">.

GIN indexeshave six support functions,three of which are optional,

asshown in <xref linkend="xindex-gin-support-table">.

(For more information see <xref linkend="GIN">.)

</para>