|From:||Matthew Wakeling <matthew(at)flymine(dot)org>|
|Subject:||GiST index performance|
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Revisiting the thread a month back or so, I'm still investigating
performance problems with GiST indexes in Postgres.
Looking at http://wiki.postgresql.org/wiki/PostgreSQL_8.4_Open_Items I'd
like to clarify the contrib/seg issue. Contrib/seg is vulnerable to
pathological behaviour which is fixed by my second patch, which can be
viewed as complete. Contrib/cube, being multi-dimensional, is not affected
to any significant degree, so should not need alteration.
A second quite distinct issue is the general performance of GiST indexes
which is also mentioned in the old thread linked from Open Items. For
that, we have a test case at
btree_gist indexes. I have a similar example with the bioseg GiST index. I
have completely reimplemented the same algorithms in Java for algorithm
investigation and instrumentation purposes, and it runs about a hundred
times faster than in Postgres. I think this is a problem, and I'm willing
to do some investigation to try and solve it.
Do you have a recommendation for how to go about profiling Postgres, what
profiler to use, etc? I'm running on Debian Linux x86_64.
Jadzia: Don't forget the 34th rule of acquisition: Peace is good for business.
Quark: That's the 35th.
Jadzia: Oh yes, that's right. What's the 34th again?
Quark: War is good for business. It's easy to get them mixed up.
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