| From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | David Rowley <dgrowleyml(at)gmail(dot)com>, pavelsivash(at)gmail(dot)com, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #16585: Wrong filtering on a COALESCE field after using GROUPING SETS |
| Date: | 2020-08-20 21:51:32 |
| Message-ID: | 87tuwxrnzm.fsf@news-spur.riddles.org.uk |
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| Thread: | |
| Lists: | pgsql-bugs |
>>>>> "Tom" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
Tom> As a stopgap measure, I think what we have to do is teach
Tom> check_output_expressions that subquery output columns are unsafe
Tom> to reference if they are not listed in all grouping sets (do I
Tom> have that condition right?).
Unless I'm missing something, it should be safe to reference output
columns that are not mentioned in any grouping set, or which are
mentioned in all grouping sets (after all expansions); but unsafe to
reference columns mentioned in some grouping sets but not others (since
these will be forced to null in the output for the sets in which they
don't appear).
--
Andrew (irc:RhodiumToad)
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