The discovered memory leak was introduced by the commit
762bf7a03b
(MDEV-22602 Disable UPDATE CASCADE for SQL constraints)
The reason why a memory leaked on running the test main.constraints
is that a statement arena was used for allocation a memory
for storing a constraint name. A constraint name is an entity having
temporary nature by its design so runtime arena should be used for its
allocation.
- CREATE TABLE ... SELECT drops constraints for columns that
are both in the create and select part.
- Fixed by copying the constraint in
Column_definiton::redefine_stage1_common()
- If one has both a default expression and check constraint for a
column, one can get the error "Expression for field `a` is refering
to uninitialized field `a`.
- Fixed by ignoring default expressions for current column when checking
for CHECK constraint
