Re: Planning large IN lists

Tom Lane wrote:
> "Atul Deopujari" <atuld(at)enterprisedb(dot)com> writes:
>> Yes, letting the planner make its own decision would seem best (in
>> accordance with what we do for different join paths). But for large IN
>> lists, a substantial part of the planner is spent in estimating the
>> selectivity of the ScalarArrayExpr by calling scalararraysel. If we are
>> not eliminating this step in processing the IN list then we are not
>> doing any optimization. Asking the planner to do scalararraysel and also
>> compute cost of any other way and choose between the two is asking
>> planner to do more work.
>
> So? Better planning usually involves more work. In any case the above
> argument seems irrelevant, because making scalararraysel more
> approximate and less expensive for long lists could be done
> independently of anything else.
>
Got you and agree with you.

--
Atul

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