Re: postgresql performance

In response to "Dave Dutcher" <dave(at)tridecap(dot)com>:

> > -----Original Message-----
> > From: SPMLINGAM
> > Subject: [PERFORM] postgresql performance
> >
> > Dear Friends,
> > I have a table with 50 lakhs records, the table has more
> > then 10 fields, i have primary key, i have select query with
> > count(*) without any condition, it takes 17 seconds.
>
> 17 seconds to scan 5 million records doesn't sound that bad to me.
> Postgresql does not store a count of records, and so it has to actually scan
> the table to count all the records. This was a design choice because select
> count(*) isn't usually used in a production system.

Note that if you need a fast count of the number of rows in a large
table, there are known workarounds to get it. Such as creating triggers
that update a count column, or using explain to get a quick estimate of
the number of rows (if that's acceptable).

--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran(at)collaborativefusion(dot)com
Phone: 412-422-3463x4023

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