> -----Original Message----- > From: Arno Brinkman [mailto:fbsupp...@abvisie.nl] > Sent: Miércoles, 28 de Octubre de 2015 21:27 > > I've to dig deep in my memory (ooh boy), but i think the > stream flag NULL is > not treated proper in this case. > > Thinking i've fixed something simular or even this in the > past, but seems > not :-/
After reading Adriano's mail, I stopped looking at v2.5. :-) I think the case can be summarized and optimized: given T = table V = the result of a selectable proc, view or derived table, if T left join V produces a null record in V caused by a non-matching outer join, then coalesce() in V should produce null immediately, no need to evaluate the arguments. A test for a solution might be select coalesce(C.f, B.f, A.f) from A left join (B left join C on ...) on ... and inserting a few records that let one join (or the two joins) produce nulls in the right side. > Simplified test case: > > SELECT > dt.* > FROM > RDB$DATABASE > LEFT JOIN (SELECT COALESCE(RDB$SECURITY_CLASS, 'NO WAY') AS > COALESCE_RET, > 'YES THIS TO' AS CONST_RET FROM RDB$DATABASE WHERE 1=1) dt ON (1 = 0); Strange, I get NULL and NULL in v2.5 and v3. C. ------------------------------------------------------------------------------ Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
