Fix constant-folding of ROW(...) IS [NOT] NULL with composite fields. The SQL standard appears to specify that IS [NOT] NULL's tests of field nullness are non-recursive, ie, we shouldn't consider that a composite field with value ROW(NULL,NULL) is null for this purpose. ExecEvalNullTest got this right, but eval_const_expressions did not, leading to weird inconsistencies depending on whether the expression was such that the planner could apply constant folding.
Also, adjust the docs to mention that IS [NOT] DISTINCT FROM NULL can be used as a substitute test if a simple null check is wanted for a rowtype argument. That motivated reordering things so that IS [NOT] DISTINCT FROM is described before IS [NOT] NULL. In HEAD, I went a bit further and added a table showing all the comparison-related predicates. Per bug #14235. Back-patch to all supported branches, since it's certainly undesirable that constant-folding should change the semantics. Report and patch by Andrew Gierth; assorted wordsmithing and revised regression test cases by me. Report: <[email protected]> Branch ------ REL9_1_STABLE Details ------- http://git.postgresql.org/pg/commitdiff/d243bf77c2d3888fb263c55317c2453cb437d1de Modified Files -------------- doc/src/sgml/func.sgml | 70 +++++++++++++++++----------------- src/backend/executor/execQual.c | 15 ++++++++ src/backend/optimizer/util/clauses.c | 12 ++++-- src/test/regress/expected/rowtypes.out | 54 ++++++++++++++++++++++++++ src/test/regress/sql/rowtypes.sql | 24 ++++++++++++ 5 files changed, 135 insertions(+), 40 deletions(-) -- Sent via pgsql-committers mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
