Re: Newbie question: ultra fast count(*) - Mailing list pgsql-performance

From Merlin Moncure
Subject Re: Newbie question: ultra fast count(*)
Date
Msg-id 6EE64EF3AB31D5448D0007DD34EEB3417DD965@Herge.rcsinc.local
Whole thread Raw
In response to Newbie question: ultra fast count(*)  (Rodrigo Madera <rodrigo.madera@gmail.com>)
List 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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