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author | Tom Lane <tgl@sss.pgh.pa.us> | 2016-07-26 15:25:02 -0400 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2016-07-26 15:25:02 -0400 |
commit | d2ef7758d2d2175509b2f49f7049e06ccd81fd57 (patch) | |
tree | eb15e70d57a39866c202808d3df2edf852004d8e /src/backend/utils/adt/ruleutils.c | |
parent | cf35406f9bce70c5f52b11122bdfb245c680000b (diff) | |
download | postgresql-d2ef7758d2d2175509b2f49f7049e06ccd81fd57.tar.gz postgresql-d2ef7758d2d2175509b2f49f7049e06ccd81fd57.zip |
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>
Diffstat (limited to 'src/backend/utils/adt/ruleutils.c')
0 files changed, 0 insertions, 0 deletions