Re: Left Join Not Using Index? - Mailing list pgsql-general

From Dennis Gearon
Subject Re: Left Join Not Using Index?
Date
Msg-id 3EA6B14C.4030406@cvc.net
Whole thread Raw
In response to Re: Left Join Not Using Index?  (Hunter Hillegas <lists@lastonepicked.com>)
List pgsql-general
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@sss.pgh.pa.us>
>>Date: Wed, 23 Apr 2003 01:30:05 -0400
>>To: Hunter Hillegas <lists@lastonepicked.com>
>>Cc: Dann Corbit <DCorbit@connx.com>, Stephan Szabo
>><sszabo@megazone23.bigpanda.com>, PostgreSQL <pgsql-general@postgresql.org>
>>Subject: Re: [GENERAL] Left Join Not Using Index?
>>
>>Hunter Hillegas <lists@lastonepicked.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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