On Thu, 2008-09-25 at 12:27 -0400, Tom Lane wrote:
> Mark Cave-Ayland <mark(dot)cave-ayland(at)siriusit(dot)co(dot)uk> writes:
> > Following up a report on the PostGIS bugtracker (also submitted to
> > pgsql-bugs here:
> > http://archives.postgresql.org/pgsql-bugs/2008-09/msg00086.php), I'm
> > wondering if there is a bug in the way that GiST indexes interact with
> > scroll cursors.
> I remember Teodor remarking that there's some problem with fetching
> backwards in a GIST indexscan, but I don't know the details --- in
> particular, no idea whether it's fixable or we need to put in something
> to prevent trying it. The latter would be a bit of a PITA since right
> now indexscans are assumed to support backwards scan regardless of
> index type.
Does ABSOLUTE 3 do a backward scan? Hope not. Just rewind and forward
scan. Presumably the bug is present when you don't do ABSOLUTE -1 first?
Seems like GIST should be able to fake a backwards scan if needed.
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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