MDEV-32866 Debug assertion failure in Item_subselect::val_bool() #3708
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Constant conditions, evaluated during optimization, should not be re-evaluated during execution. However, a bug led to some inexpensive conditions being incorrectly marked for evaluation at execution by `JOIN::exec_const_cond`. This resulted in redundant subselect executions and triggered the assertion. The fix ensures that only conditions requiring deferred evaluation are saved to JOIN::exec_const_cond, maintaining the correct execution flow
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Constant subqueries, once evaluated during optimization, should not be re-evaluated neither during optimization, nor during execution. Nevertheless, at some scenarios re-evaluation was possible, since previously evaluated constant IN-predicates were not properly marked. This commit implements proper marking of subqueries within constant conditions, preventing their re-evaluation
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Description
Constant conditions, evaluated during optimization, should not be re-evaluated during execution. However, a bug led to some inexpensive conditions being incorrectly marked for evaluation at execution by
JOIN::exec_const_cond. This resulted in redundant subselect executions and triggered the assertion. The fix ensures that only conditions requiring deferred evaluation are saved to JOIN::exec_const_cond, maintaining the correct execution flowIf the changes are not amenable to automated testing, please explain why not and carefully describe how to test manually.
Basing the PR against the correct MariaDB version
mainbranch.PR quality check