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@tao11.riddles.org.uk>
wrote:

> >>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.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