| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
| Cc: | sindysenorita(at)gmail(dot)com, pgsql-bugs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: BUG #17618: unnecessary filter column <> text even after adding index |
| Date: | 2022-09-20 23:55:59 |
| Message-ID: | 946195.1663718159@sss.pgh.pa.us |
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| Thread: | |
| Lists: | pgsql-bugs |
I wrote:
> I wonder if that isn't backwards, ie we should prefer to put duplicates
> in bitmapqualorig (the recheck condition) instead of qpqual (the filter).
> If my head is screwed on correctly today, that should allow us to skip
> checking the condition much of the time, and the skip would be safe
> if the index is correctly asserting that no recheck is needed.
Flipping the removal around has the effect I expected on the plan shape,
but some of the regression test queries now give the wrong answer, so
there's something faulty about that analysis.
regards, tom lane
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