Shrirang Chitnis <shrirang.chit...@hovservices.com> writes:
> Bryce,
> The two queries are different:
I suspect the second one is a typo and not what he really wanted.
> WHERE (contexts.parent_key = 392210
> OR contexts.context_key IN
> (SELECT collection_data.context_key
> FROM collection_data
> WHERE collection_data.collection_context_key = 392210)
The only really effective way the planner knows to optimize an
"IN (sub-SELECT)" is to turn it into a semi-join, which is not possible
here because of the unrelated OR clause. You might consider replacing
this with a UNION of two scans of "contexts". (And yes, I know it'd be
nicer if the planner did that for you.)
regards, tom lane
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