Re: Really dumb planner decision - Mailing list pgsql-performance

From Tom Lane
Subject Re: Really dumb planner decision
Date
Msg-id 16192.1239889768@sss.pgh.pa.us
Whole thread Raw
In response to Re: Really dumb planner decision  (Merlin Moncure <mmoncure@gmail.com>)
Responses Re: Really dumb planner decision
Re: Really dumb planner decision
List pgsql-performance
Merlin Moncure <mmoncure@gmail.com> writes:
> On Thu, Apr 16, 2009 at 8:05 AM, Matthew Wakeling <matthew@flymine.org> wrote:
>> That solves the problem. So, a view is treated as a subquery then?

> no...the view is simply inlined into the query (think C macro) using
> the rules.  You just bumped into an arbitrary (and probably too low)
> limit into the number of tables the planner can look at in terms of
> optimizing certain types of plans.

Bear in mind that those limits exist to keep you from running into
exponentially increasing planning time when the size of a planning
problem gets big.  "Raise 'em to the moon" isn't really a sane strategy.
It might be that we could get away with raising them by one or two given
the general improvement in hardware since the values were last looked
at; but I'd be hesitant to push the defaults further than that.

            regards, tom lane

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