Re: Can the query planner create indexes?

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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> 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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