Re: Automatic optimization of IN clauses via INNER JOIN

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On 17/12/2009 11:57 PM, Tom Lane wrote:
Thomas Hamilton<thomashamilton76@xxxxxxxxx>  writes:
But in our testing under the same optimization and conditions INNER JOIN is significantly outperforming IN.

[ shrug... ]  You haven't provided any details, so it's impossible to
offer any useful advice.

In other words: can we discuss this with reference to a specific case? Please provide your queries, your EXPLAIN ANALYZE output, and other relevant details as per:

  http://wiki.postgresql.org/wiki/SlowQueryQuestions

I'd be interested in knowing whether the planner can perform such transformations and if so why it doesn't myself. I have the vague feeling there may be semantic differences in the handling of NULL but I can't currently seem to puzzle them out.

--
Craig Ringer

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