Re: count * performance issue

buy every time i need to put ANALYZE...
this takes the same time as count(*) takes, what is the use ??

On Thu, Mar 6, 2008 at 11:45 AM, Shoaib Mir <shoaibmir(at)gmail(dot)com> wrote:

> On Thu, Mar 6, 2008 at 5:08 PM, A. Kretschmer <
> andreas(dot)kretschmer(at)schollglas(dot)com> wrote:>
>
> > > 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...
> >
> > There aren't a general solution. If you realy need the exact count of
> > tuples than you can play with a TRIGGER and increase/decrease the
> > tuple-count for this table in an extra table.
> >
> >
> >
> Or do something like:
>
> ANALYZE tablename;
> select reltuple from pg_class where relname = 'tablename';
>
> That will also return the total number of rows in a table and I guess
> might be much faster then doing a count(*) but yes if trigger can be an
> option that can be the easiest way to do it and fastest too.
>
> --
> Shoaib Mir
> Fujitsu Australia Software Technology
> shoaibm[(at)]fast(dot)fujitsu(dot)com(dot)au