>   http://archives.postgresql.org/pgsql-hackers/2007-03/msg00265.php
>   http://archives.postgresql.org/pgsql-hackers/2007-03/msg01214.php
>   http://archives.postgresql.org/pgsql-patches/2007-05/msg00013.php
>   http://archives.postgresql.org/pgsql-hackers/2007-07/msg00741.php
>   http://archives.postgresql.org/pgsql-hackers/2007-08/msg00014.php
>   http://archives.postgresql.org/pgsql-hackers/2007-08/msg00487.php
> * Allow index scans to return matching index keys
>
>   http://archives.postgresql.org/pgsql-hackers/2007-03/msg01079.php
>
>   http://archives.postgresql.org/pgsql-patches/2007-10/msg00166.php
>   http://archives.postgresql.org/pgsql-patches/2008-01/msg00049.php