Re: How much expensive are row level statistics?

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От Merlin Moncure
Тема Re: How much expensive are row level statistics?
Дата
Msg-id 6EE64EF3AB31D5448D0007DD34EEB3417DDB39@Herge.rcsinc.local
обсуждение исходный текст
Ответ на How much expensive are row level statistics?  (Carlos Benkendorf <carlosbenkendorf@yahoo.com.br>)
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> Now there goes Tom with his skeptical eye again, and here comes me
> saying "oops" again.  Further tests show that for this application

I made the same mistake, fwiw.  The big hit comes with command_string.
However, row level stats bring a big enough penalty (~10% on my usage)
that I keep them turned off.  The penalty is not just run time either,
but increased cpu time.  It just isn't an essential feature so unless it
causes near zero extra load it will stay off on my servers.

Additionally, back when I was testing the win32/pg platform I was
getting random restarts of the stats collector when the server was under
high load and row_level stats were on.  This was a while back so this
issue may or may not be resolved...it was really nasty because it
cleared out pg_stats_activity which in turn ruined my admin tools.  I
should probably give that another look.

Merlin

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