Re: Left Join Not Using Index?

From: Dennis Gearon <gearond(at)cvc(dot)net>
To: Hunter Hillegas <lists(at)lastonepicked(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Dann Corbit <DCorbit(at)connx(dot)com>, Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>, PostgreSQL <pgsql-general(at)postgresql(dot)org>
Subject: Re: Left Join Not Using Index?
Date: 2003-04-23 15:29:16
Message-ID: 3EA6B14C.4030406@cvc.net
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I think he is saying that efforts in data design, and query design are called for.

Hunter Hillegas wrote:
> So, what you're basically saying is that my best bet for improving the speed
> of a query to get this result set is to tweak my settings and get faster
> hardware?
>
>
>>From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>>Date: Wed, 23 Apr 2003 01:30:05 -0400
>>To: Hunter Hillegas <lists(at)lastonepicked(dot)com>
>>Cc: Dann Corbit <DCorbit(at)connx(dot)com>, Stephan Szabo
>><sszabo(at)megazone23(dot)bigpanda(dot)com>, PostgreSQL <pgsql-general(at)postgresql(dot)org>
>>Subject: Re: [GENERAL] Left Join Not Using Index?
>>
>>Hunter Hillegas <lists(at)lastonepicked(dot)com> writes:
>>
>>>Can anyone point me in another direction to optimize this
>>
>>AFAICS you cannot improve that without changing the query structure
>>and/or the database layout. Because the WHERE clause is a bunch of OR'd
>>conditions, it's useless for restricting either individual table scan
>>making up the join --- there is really no implementation short of
>>forming the entire join described by the FROM ... JOIN ... ON ... part
>>of the query and then testing each individual row against the WHERE
>>clause. While that is the abstract semantic model implied by the SQL
>>spec, it's not exactly how you want a query to really be done :-(.
>>
>>regards, tom lane
>
>
>
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