Hello all,
> -----Original Message-----
> From: owner-pgsql-hackers@postgreSQL.org
> [mailto:owner-pgsql-hackers@postgreSQL.org]On Behalf Of Hannu Krosing
> Sent: Thursday, February 04, 1999 3:43 AM
> To: Jan Wieck
> Cc: hackers@postgreSQL.org
> Subject: Re: [HACKERS] 6.5 beta and ORDER BY patch
>
[snip]
>
> After that the reverse index scans, so that the index that are
> backwards can also be used for sorting.
> BTW, can this be easily implemented/effective in PostgreSQL or are
> our btree indexes optimised for forward scans ?
>
PostgreSQL seems to have the ability to scan Index backward
because we can execute "fetch backward" command.
IMHO _bt_first() fucntion used to find first item in a scan should
be changed to work well in case of backward positioning.
I think this change also gives the partial solution for the problem
[ [HACKERS] Cursor Movement - Past the End ] reported by
David Hartwig.
I have a sample code for this change.
I can send it if someone want to check or test it.
Thanks.
Hiroshi Inoue
Inoue@tpf.co.jp