Re: Reducing overhead for repeat de-TOASTing - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Reducing overhead for repeat de-TOASTing
Date
Msg-id 12180.1213670046@sss.pgh.pa.us
Whole thread Raw
In response to Re: Reducing overhead for repeat de-TOASTing  (Stephen Frost <sfrost@snowman.net>)
List pgsql-hackers
Stephen Frost <sfrost@snowman.net> writes:
> * Tom Lane (tgl@sss.pgh.pa.us) wrote:
>> Comments, better ideas?  Anyone think this is too much trouble to take
>> for the problem?

> I definitely think it's worth it, even if it doesn't handle an
> inline-compressed datum.

Yeah.  I'm not certain how much benefit we could get there anyway.
If the datum isn't out-of-line then there's a small upper limit on how
big it can be and hence a small upper limit on how long it takes to
decompress.  It's not clear that a complicated caching scheme would
pay for itself.

The profile shown here:
http://postgis.refractions.net/pipermail/postgis-devel/2008-June/003081.html
shows that the problem the PostGIS guys are looking at is definitely an
out-of-line case (in fact, it looks like the datum wasn't even compressed).
        regards, tom lane


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