MDEV-19580 Unrelated JOINs corrupt usage of 'WHERE function() IN (subquery)'
Handling of top level conjuncts in WHERE whose used_tables() contained RAND_TABLE_BIT in the function make_join_select() was incorrect. As a result if such a conjunct referred to fields non of which belonged to the last joined table it was pushed twice. (This could be seen for a test case from subselect.test whose output was changed after this patch had been applied. In 10.1 when running EXPLAIN FORMAT=JSON for the query from this test case we clearly see that one of the conjuncts is pushed twice.) This fact by itself was not good. Besides, if such a conjunct was pushed to a table that was the result of materialization of a semi-join the query could return a wrong result set. In particular we could watch it for queries with semi-join subqueries whose left parts used stored functions without "deterministic' specifier.
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