Re: Automatic optimization of IN clauses via INNER JOIN

On 17/12/2009 11:57 PM, Tom Lane wrote:
> Thomas Hamilton<thomashamilton76@yahoo.com>  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