Re: [HACKERS] Slow - grindingly slow - query

On Fri, Nov 12, 1999 at 09:58:14AM -0500, Tom Lane wrote:
> Brian Hirt <bhirt(at)mobygames(dot)com> writes:
> > Can't the rewrite engine recognize a simple case like the
> > one above and rewrite it to use exists and not exists with the proper
> > joins? Or possibly the optimizer can generate a better plan?
>
> This is on the TODO list, and will get done someday. IMHO it's not as
> urgent as a lot of the planner/optimizer's other shortcomings, because
> it can usually be worked around by revising the query.
>
> If it's bugging you enough to go fix it now, contributions are always
> welcome ;-)
>

Okay, what would be the correct approach to solving the problem,
and where would be a good place to start? I'v only been on this list
for a few weeks, so I'm missed discussion on the approach to solving
this problem. Should this change be localized to just the planner?
Should the rewrite system be creating a different query tree? Will both
need to be changed? If a lot of work is being done to this part of
the system, is now a bad time to try this work?

I'm willing to jump in to this, but I may take a while to figure it out
and ask a lot of questions that are obvious to the hardened postgres
programmer. I'm not famaliar with the postgres code, yet.

-brian

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