Re: Can relational alegbra perform bulk operations?

From: Clifford Heath <no.spam_at_please.net>
Date: Thu, 01 Oct 2009 11:01:59 +1000
Message-ID: <jcTwm.13128$Bl2.1664_at_newsfe14.iad>



Walter Mitty wrote:
> When code jockeys set out to learn SQL, the hardest thing to get them to
> learn is to refrain from coding in such a way as to gove implicit "hints" to
> the optimizer in the way they express their queries.

Unfortunately MySQL is still teaching the new generation that the order of joins actually matters.

> Getting programmers to think in terms of "what" rather than "how" has been a
> continuing struggle since the 1950s.

Now you're singing my song. This is one of the most fundamental problems of the industry, going far beyond just the database world.

I've had to use hints in MSSQL (2000) in order to avoid a nasty optimiser bug where it ignores the obvious index that can make a join work. This was with a DELETE FROM a WHERE NOT EXISTS(...) (an anti-semi-join).

-- 
Clifford Heath, Data Constellation, http://dataconstellation.com
Agile Information Management and Design
Received on Wed Sep 30 2009 - 20:01:59 CDT

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