yjhjstz opened a new pull request, #1981:
URL: https://github.com/apache/cloudberry/pull/1981
On an assert-enabled build the following query crashed the QD with
FailedAssertion("pselec >= 0.0 && pselec <= 1.0", costsize.c:5506):
CREATE TABLE m1(c0 inet);
CREATE TABLE m2(c0 inet);
INSERT INTO m2 VALUES ('88.147.138.141'), ('76.163.212.11'),
('214.10.65.144');
ANALYZE m1, m2;
SELECT COUNT(*) FROM ONLY m1 LEFT OUTER JOIN m2 ON true
WHERE (m1.c0 IS NOT NULL)
OR (m2.c0 BETWEEN SYMMETRIC '75.175.243.19' AND '230.9.216.68');
The pushed-down WHERE clause is an OR of an IS NOT NULL test on the outer
side (selectivity 0.999, no stats on the empty table) and a range pair on the
nullable side. When clauselist_selectivity() merges the range pair (hibound +
lobound - 1) it adds back the column's null fraction to undo the double
exclusion of NULLs, and it does so by calling nulltestsel(IS_NULL, ...,
jointype). GPDB's nulltestsel() special-cases IS NULL under an outer join and
returns 0.5 (a guess for the anti-join "WHERE inner.col IS NULL" pattern,
removed upstream in e006a24a), so the range pair comes out as 0.99 + 0.5 = 1.49
instead of 0.99 + 0.0. Combining that with the IS NOT NULL arm via s1 + s2 -
s1*s2 gives 1.00049, which adjust_selectivity_for_nulltest() asserts on.
Two changes:
1. In clauselist_selectivity_ext(), ask nulltestsel() for the column's real
null fraction by passing JOIN_INNER. The range-pair correction is a
statistical adjustment, not an IS NULL predicate evaluated at the join level,
so the outer-join guess never belonged here. Before this, every range pair
evaluated under an outer join was inflated by an absolute 0.5; after it, a LEFT
JOIN ON clause with a range condition gets the same estimate as the equivalent
inner join. This matches upstream behaviour, where nulltestsel() ignores
jointype.
2. Selectivities are probabilities, so also clamp jselec and pselec to [0,
1] in calc_joinrel_size_estimate() before handing them to
adjust_selectivity_for_nulltest(), so round-off in the OR combination can never
trip the assertion again.
Add the SQLancer query to bfv_planner as a regression test.
Fixes #1950
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