Re: [SQL] Good Optimization - Mailing list pgsql-sql

From Bruce Momjian
Subject Re: [SQL] Good Optimization
Date
Msg-id 199907071801.OAA05018@candle.pha.pa.us
Whole thread Raw
In response to Re: [SQL] Good Optimization  (wieck@debis.com (Jan Wieck))
List pgsql-sql
> >     There is a simple way to optimize SQL queries involving joins to
> > PostgreSQL that I think should be handled by Postgre?  If one is joining
> > a tables a,b on attribute "x" and if one has something like x=3 then it
> > helps A LOT to say: a.x=3 and b.x=3 in addition to saying a.x=b.x ...
> > The example below shoulds the radical speed gain of doing this, and I
> > think it isn't something real obvious to most people...
> >
> >     Of course it could just be a common thing to do in SQL, anyway, just
> > thought I'd let you all know what I discovered.
> >
> >
> >
> > Here is an example:
> > [...]
> 
> Hmmmmm,
> 
>     wouldn't   it   be  nice  to  do  such  things  automagically
>     (rewriter? planner?).

Added to TODO:
* In WHERE x=3 AND x=y, add y=3              


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