Re: forcing use of more indexes (bitmap AND) - Mailing list pgsql-general

On Fri, 2008-03-14 at 00:50 -0600, Scott Marlowe wrote:
> On Fri, Mar 14, 2008 at 12:28 AM, Ow Mun Heng <Ow.Mun.Heng@wdc.com> wrote:
> > query is something like this
> >
> >         Select *
> >         from v_test
> >         where acode Like 'PC%'
> >         and rev = '0Q'
> >         and hcm = '1'
> >         and mcm = 'K'
> >
> >  where acode, rev, hcm, mcm are all indexes.
> >
> >  Currently this query is only using the rev and mcm for the bitmapAND.
> >  it then does a bitmap heap scan using the acode and the hcm indexes.
> >
> >  I would like to try to see if forcing the planner to favour heavier usage of the indexes would yield faster
results.
> >
> >  I've tried lowering
>
> Would setting enable_bitmapscan=off do that?  I'm not being sarcastic,
> I really don't know.

This is even worst as the planner would only use 1 index.