From: | Vadim Mikheev <vadim(at)krs(dot)ru> |
---|---|
To: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
Cc: | "Vadim B(dot) Mikheev" <vadim(at)sable(dot)krasnoyarsk(dot)su>, PostgreSQL-development <hackers(at)postgreSQL(dot)org> |
Subject: | Re: [HACKERS] OR with multi-key indexes |
Date: | 1998-08-01 12:12:18 |
Message-ID: | 35C30622.4E86FA49@krs.ru |
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Lists: | pgsql-hackers |
Bruce Momjian wrote:
>
> Here is a comment in path/indxpath.c that says they don't want to use
> multi-key indexes with OR clauses. Of course, we now support multi-key
> indexes, and this code was disabled anyway because it was broken. (In
> fact, it was disabled by having SingleAttributeIndex() always return
> false.
>
> Is there any reason we can't use multi-key indexes if the first key
> matches our OR column? I don't see why not. Also, I don't know how to
^^^^^^^^^^^^^^^^^^^
Me too.
> handle the case where we specify the first key of a multi-key index in
> an AND clause, and specify the second key in an OR clause because the
What do you mean? Example please...
> AND's are handled in a separate are of the code. Any ideas how to
> implement this? (Of course, the code would still use the index for the
> AND, but I don't know how to bring the AND case into my OR index clause
> processing area.)
Vadim
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