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MDEV-30080 Wrong result with LEFT JOINs involving constant tables

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The reason things fails in 10.5 and above is that test_quick_select()
returns -1 (impossible range) for empty tables if there are any
conditions attached.

This didn't happen in 10.4 as the cost for a range was more than for
a table scan with 0 rows and get_key_scan_params() did not create any
range plans and thus did not mark the range as impossible.

The code that checked the 'impossible range' conditions did not take
into account all cases of LEFT JOIN usage.

Adding an extra check if the table is used with an ON condition in case
of 'impossible range' fixes the issue.
This commit is contained in:
Monty
2023-01-12 18:45:40 +02:00
parent 3316a54db3
commit 0eca91ab75
2 changed files with 3 additions and 0 deletions
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mysql-test/main/join.result
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@ -3435,6 +3435,7 @@ SELECT COUNT(*) FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.b = t3.c) ON t1.a = t2.
COUNT(*)
2
DROP TABLE t1, t2, t3;
# End of 10.5 tests
#
# MDEV-30256 Wrong result (missing rows) upon join with empty table
#