| From: | "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> |
|---|---|
| To: | "Rodrigo Madera" <rodrigo(dot)madera(at)gmail(dot)com> |
| Cc: | <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Newbie question: ultra fast count(*) |
| Date: | 2005-11-28 13:31:06 |
| Message-ID: | 6EE64EF3AB31D5448D0007DD34EEB3417DD965@Herge.rcsinc.local |
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| Thread: | |
| Lists: | pgsql-performance |
> I have been reading all this technical talk about costs and such that
> I don't (_yet_) understand.
>
> Now I'm scared... what's the fastest way to do an equivalent of
> count(*) on a table to know how many items it has?
Make sure to analyze the database frequently and check pg_class for
reltuples field. This gives 0 time approximations of # row in table at
the time of the last analyze.
Many other approaches...check archives. Also your requirements are
probably not as high as you think they are ;)
Merlin
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