On Thu, Dec 17, 2009 at 9:20 PM, Craig Ringer
> On 17/12/2009 11:57 PM, Tom Lane wrote:
>> Thomas Hamilton<thomashamilton76(at)yahoo(dot)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:
> 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.
NOT IN is the only that really kills you as far as optimization is
concerned. IN can be transformed to a join. NOT IN forces a NOT
(subplan)-type plan, which bites - hard.
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