| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Elvis Pranskevichus <elprans(at)gmail(dot)com> |
| Cc: | PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org>, David Rowley <dgrowleyml(at)gmail(dot)com> |
| Subject: | Re: BUG #17213: Wrong result from a query involving Merge Semi Join and Memoize |
| Date: | 2021-10-05 01:21:21 |
| Message-ID: | 4022669.1633396881@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Elvis Pranskevichus <elprans(at)gmail(dot)com> writes:
> On Monday, October 4, 2021 5:14:47 PM PDT David Rowley wrote:
>>> It appears a combination of Merge Semi Join and Memoize in
>>> PostgreSQL 14 produces incorrect results on a particular query.
> It seems like a very particular set of stats is causing the plan there,
> as running ANALYZE turns the query into a Nested Loop Semi Join.
Surely this plan tree is broken on its face? The inner side of
a mergejoin has to be able to support mark/restore, and nestloop
doesn't (cf ExecSupportsMarkRestore, as well as assertions in
nodeNestloop). It looks to me like somebody removed an essential
plan-time check.
regards, tom lane
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