Tom Lane 4452000f31 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: <20160708024746.1410.57282@wrigleys.postgresql.org>		2016-07-26 15:25:02 -04:00
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src	Fix constant-folding of ROW(...) IS [NOT] NULL with composite fields.	2016-07-26 15:25:02 -04:00
bug.template	Stamp 9.6beta3.	2016-07-18 16:54:26 -04:00
KNOWN_BUGS
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MISSING_FEATURES
TODO