| From: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: AW: pg_index.indislossy |
| Date: | 2001-07-10 14:53:11 |
| Message-ID: | Pine.LNX.4.30.0107101651370.677-100000@peter.localdomain |
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| Lists: | pgsql-hackers |
Bruce Momjian writes:
> > > > > Can someone tell me what we use indislossy for?
> >
> > Ok, so the interpretation of this field is:
> > A match in the index needs to be reevaluated in the heap tuple data,
> > since a match in the index does not necessarily mean, that the heap tuple
> > matches.
> > If the heap tuple data matches, the index must always match.
AFAIK, this is true for all indexes in PostgreSQL, because index rows
don't store the transactions status. Of course those are two different
underlying reasons why a heap lookup is always necessary, but there
shouldn't be any functional difference in the current implementation.
--
Peter Eisentraut peter_e(at)gmx(dot)net http://funkturm.homeip.net/~peter
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