Re: Planner not using column limit specified for one column for another column equal to first - Mailing list pgsql-performance

From Matthew Wakeling
Subject Re: Planner not using column limit specified for one column for another column equal to first
Date
Msg-id alpine.DEB.2.00.1004191043280.27544@aragorn.flymine.org
Whole thread Raw
In response to Re: Planner not using column limit specified for one column for another column equal to first  (Віталій Тимчишин)
List pgsql-performance
On Sat, 17 Apr 2010, Віталій Тимчишин wrote:
> As of making planner more clever, may be it is possible to introduce
> division on "fast queries" and "long queries", so that if after fast
> planning cost is greater then some configurable threshold, advanced planning
> techniques (or settings) are used. As far as I have seen in this list, many
> techniques are not used simply because they are too complex and could make
> planning take too much time for really fast queries, but they are vital for
> long ones.

+1. That's definitely a good idea in my view. The query optimiser I wrote
(which sits on top of Postgres and makes use of materialised views to
speed up queries) uses a similar approach - it expends effort proportional
to the estimated cost of the query, as reported by EXPLAIN.

Matthew

--
 To most people, solutions mean finding the answers. But to chemists,
 solutions are things that are still all mixed up.

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