Avoid NullTest deduction for clone clauses In commit b262ad440, we introduced an optimization that reduces an IS NOT NULL qual on a column defined as NOT NULL to constant true, and an IS NULL qual on a NOT NULL column to constant false, provided we can prove that the input expression of the NullTest is not nullable by any outer join. This deduction happens after we have generated multiple clones of the same qual condition to cope with commuted-left-join cases.
However, performing the NullTest deduction for clone clauses can be unsafe, because we don't have a reliable way to determine if the input expression of a NullTest is non-nullable: nullingrel bits in clone clauses may not reflect reality, so we dare not draw conclusions from clones about whether Vars are guaranteed not-null. To fix, we check whether the given RestrictInfo is a clone clause in restriction_is_always_true and restriction_is_always_false, and avoid performing any reduction if it is. There are several ensuing plan changes in predicate.out, and we have to modify the tests to ensure that they continue to test what they are intended to. Additionally, this fix causes the test case added in f00ab1fd1 to no longer trigger the bug that commit fixed, so we also remove that test case. Back-patch to v17 where this bug crept in. Reported-by: Ronald Cruz <c...@rentec.com> Diagnosed-by: Tom Lane <t...@sss.pgh.pa.us> Author: Richard Guo <guofengli...@gmail.com> Reviewed-by: Tom Lane <t...@sss.pgh.pa.us> Discussion: https://postgr.es/m/f5320d3d-77af-4ce8-b9c3-4715ff33f...@rentec.com Backpatch-through: 17 Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/bc5a08af3c44b4529d5dba5e26755e8cfbb0d3c7 Modified Files -------------- src/backend/optimizer/plan/initsplan.c | 18 ++++ src/test/regress/expected/predicate.out | 175 ++++++++++++++++++++++---------- src/test/regress/sql/predicate.sql | 56 ++++++++-- 3 files changed, 187 insertions(+), 62 deletions(-)
