Re: BUG #16585: Wrong filtering on a COALESCE field after using GROUPING SETS

On Fri, Aug 21, 2020 at 5:51 AM Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>
wrote:

> >>>>> "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,

I think such columns usually are aggregation expr, If we want to push down
a qual which reference to an aggregation expr, we have to push down
to having cause, However I am not sure such pushing down really helps.

> or which are
> mentioned in all grouping sets (after all expansions);

--
Best Regards
Andy Fan