MDEV-40143: st_isvalid() does not clear NULL state between rows#5313
MDEV-40143: st_isvalid() does not clear NULL state between rows#5313DaveGosselin-MariaDB wants to merge 1 commit into
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The st_isvalid() function evaluates nullability on every row. Previously, it would preserve potentially stale null state between rows, so the first row yielding a null result for st_isvalid() would propagate to the results for the remaining rows. Implementation-wise, this patch changes the Item_func_isvalid::val_int method implementation to work like Item_func_validate::val_str in that it assumes that the method will indicate a null result for the row unless it returns a non-null result, at which point it clears the null_value flag.
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Code Review
This pull request fixes the handling of the null_value flag in Item_func_isvalid::val_int() by initializing it to 1 and only resetting it to 0 upon a successful validity check. It also adds corresponding test cases to verify this behavior. The review feedback correctly identifies a potential null pointer dereference if args[0]->val_str() returns NULL, suggesting a defensive check to prevent a server crash.
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The st_isvalid() function evaluates nullability on every row. Previously, it would preserve potentially stale null state between rows, so the first row yielding a null result for st_isvalid() would propagate to the results for the remaining rows.
Implementation-wise, this patch changes the Item_func_isvalid::val_int method implementation to work like Item_func_validate::val_str in that it assumes that the method will indicate a null result for the row unless it returns a non-null result, at which point it clears the null_value flag.