On 01/10/2018 09:46, Alex Peshkoff via Firebird-devel wrote: > On 10/01/18 12:44, Dimitry Sibiryakov wrote: >> 01.10.2018 11:24, Pavel Cisar wrote: >>> Aggregates could produce various single-value outputs >> >> Why to limit them to single value? Some aggregates could profit if >> they are able to return more values at once. For example, avg + >> deviation. >> > > That really can improve performance. Specially interesting when > dealing with emulated decfloat datatype. > And I see no tech difference with > create aggregate function ... > and > create aggregate procedure ... > Procedure's body may follow exactly same rules. >
A single (aggregate) function call should not produce (describe) more than one column in a query. Two-functions-in-one could be supported with ROW type. When ROW type is implemented, it should be implemented to work in all cases supporting others types, like standard function and aggregate functions. Adriano Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
