Re: EXISTS optimization

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> If you want that, try rewriting the EXISTS to an IN:
>>
>> AND ("H"."tranNo", "H"."countyNo") IN
>> (
>> SELECT "D"."tranNo", "D"."countyNo" FROM "TranDetail" "D"
>> WHERE "D"."caseNo" LIKE '2006TR%'
>> )

> That's the good news. The bad news is that I operate under a
> management portability dictate which doesn't currently allow that
> syntax, since not all of the products they want to cover support it.

Which part of it don't they like --- the multiple IN-comparisons?

> I tried something which seems equivalent, but it is running for a very
> long time.
> AND "H"."tranNo" IN
> (
> SELECT "D"."tranNo" FROM "TranDetail" "D"
> WHERE "D"."caseNo" LIKE '2006TR%'
> AND "D"."countyNo" = "H"."countyNo"
> )

No, that's not gonna accomplish a darn thing, because you've still got
a correlated subquery (ie, a reference to outer "H") and so turning the
IN into a join doesn't work.

regards, tom lane