count * performance issue - Mailing list pgsql-performance

From sathiya psql
Subject count * performance issue
Date
Msg-id f966c2ee0803052143k4570d771o6c300647d3b987d@mail.gmail.com
Whole thread Raw
Responses Re: count * performance issue  (Chris <dmagick@gmail.com>)
Re: count * performance issue  ("A. Kretschmer" <andreas.kretschmer@schollglas.com>)
List pgsql-performance
count(*) tooks much time...

but with the where clause we can make this to use indexing,... what where clause we can use??

Am using postgres 7.4 in Debian OS with 1 GB RAM,

am having a table with nearly 50 lakh records,

it has more than 15 columns, i want to count how many records are there, it is taking nearly 17 seconds to do that...

i know that to get a approximate count we can use
         SELECT reltuples FROM pg_class where relname = TABLENAME;

but this give approximate count, and i require exact count...

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