From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Chris Browne <cbbrowne(at)acm(dot)org> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Thoughts on statistics for continuously advancing columns |
Date: | 2009-12-30 22:35:02 |
Message-ID: | 9435.1262212502@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Chris Browne <cbbrowne(at)acm(dot)org> writes:
> I find it curious that ANALYZE *would* take a long time to run.
> After all, its sampling strategy means that, barring having SET
> STATISTICS to some ghastly high number, it shouldn't need to do
> materially more work to analyze a 1TB table than is required to analyze
> a 1GB table.
Right. The example JD quotes in this thread compares a 35MB table
to a 350MB one, and the difference is all about having crossed the
threshold of what would fit in his available RAM. There isn't going
to be much difference in the ANALYZE time for "big" versus "very big"
tables. (There might, however, be a difference in the quality of
the resulting stats :-()
regards, tom lane
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