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Re: AW: [HACKERS] OR clause status report

From: Vadim Mikheev <vadim(at)krs(dot)ru>
To: Andreas Zeugswetter <andreas(dot)zeugswetter(at)telecom(dot)at>, Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>, PostgreSQL-development <hackers(at)postgreSQL(dot)org>
Subject: Re: AW: [HACKERS] OR clause status report
Date: 1998-07-31 14:02:59
Message-ID: 35C1CE93.E744800B@krs.ru (view raw or flat)
Thread:
Lists: pgsql-hackers
Vadim Mikheev wrote:
> 
> Andreas Zeugswetter wrote:
> >
> > Vadim wrote:
> > >Bruce Momjian wrote:
> > >>
> > >> I have succeeded in making OR clauses use indexes.  I have not dealt
> > >> with some of the more complex issues like x=3 or y=5 as Vadim mentioned,
> > >> but at least it works.
> > >>
> > >>         test=> select * from test where x=102532 or x=102533;
> > >
> > >But did you care about the case when two indices (on test(x) and
> > >on test(y)) exist ?
> >
> > Do you mean using two indices in one access plan, 
>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This.

Actually, I meant NOT USING indices if both exist, because of
currently there is no check that tuples returned by second index 
were not returned by first.

> > or the decision which index to use ?

Either both indices should be used or no one...

Also, Bruce, did you test the case (x = 5 or x > 4) ?
What about (x = 5 or x = 5)? - I'm not sure does cnfify()
get rid of duplicates or not...

Vadim

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Next:From: Vince VielhaberDate: 1998-07-31 14:05:14
Subject: Re: [HACKERS] OR clause status report
Previous:From: Vadim MikheevDate: 1998-07-31 13:46:28
Subject: Re: [HACKERS] OR clause status report

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