From: | tv(at)fuzzy(dot)cz |
---|---|
To: | "Grzegorz Jaśkiewicz" <gryzman(at)gmail(dot)com> |
Cc: | tv(at)fuzzy(dot)cz, "Jeremy Harris" <jgh(at)wizmail(dot)org>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Can the query planner create indexes? |
Date: | 2010-12-21 15:21:05 |
Message-ID: | 0bceac06db98414e27da53b342aca79e.squirrel@sq.gransy.com |
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Thread: | |
Lists: | pgsql-general |
> I don't think planner should do things like creating an index. But it
> might hint at doing it in the logs.
> There was a discussion around that sort of feature on -hackers not so
> long time ago. I don't remember what the conclusion was, but probably
> that it just isn't worth wasting planner's cycles when you execute a
> query.
Yes, that would be a much better solution, definitely. Something like
'watch seq-scan nodes and if the number of matching rows is much smaller
than the total number, put a HINT into log.'
I was thinking about doing something like this for correlated columns
(when the number of matching rows is severely underestimated). But that's
far in the future.
Tomas
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