"David Johnston" <polobo@xxxxxxxxx> writes: > The first case is: > SELECT COALESCE( (SELECT), (SELECT) ); I am not sure exactly what the parentheses surrounding the scalar-sub-SELECTs do (turn them into anonymously typed rows?) but if the first scalar-sub-select results in a non-null result then the second one should not be executed. Indeed, COALESCE will not execute the second sub-select at runtime, but that doesn't particularly matter here. What matters is that "ps3(2)" qualifies to be pre-evaluated (folded to a constant) at plan time. So that happens, and the RAISE message comes out, at plan time. What's left at run time is SELECT COALESCE( (SELECT 1), (SELECT 2) ); and indeed the "SELECT 2" is skipped at that point, as is visible in the EXPLAIN ANALYZE measurements. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
