15.10.2010 22:29, Tom Lane:
Nikolai Zhubr<n-a-zh...@yandex.ru> writes:
So, "in (1, 2)" condition is not in Index Cond anymore! Why is that? How
can I push it back?
It thinks the indexscan condition is sufficiently selective already.
An = ANY condition like that will force multiple index searches,
one for each of the OR'd possibilities, so it's far from "free" to add
it to the index condition. The planner doesn't think it's worth it.
Aha, ok. It makes sense then. Is this specific case (=ANY in index cond)
described somewhere with reasonable detail? I always try to RTFM first
and most of the time I can find pretty good hints in the regular manual
already (sufficient as a starting point at least) but this specific
topic seems to be somewhat mysterious.
Perhaps on your real query it is, but there's not much point in
debating about the behavior on this toy table; without realistic
table sizes and up-to-date stats it's impossible to say whether that
choice is correct or not.
SELECT version();
PostgreSQL 8.3.1, compiled by Visual C++ build 1400
You really, really, really ought to be running 8.3.something-newer.
We didn't put out the last 11 8.3.x bugfix updates just because
we didn't have anything better to do.
Yes, I know, and I do appreciate the efforts of postgresql devels to
create updates for older versions too.
This server is internal-only (so it does not see any real world yet).
Anyway, I hope to update everything to 9.0.1 soon.
Thank you!
Nikolai
regards, tom lane
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