Re: [HACKERS] Reducing overhead for repeat de-TOASTing

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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