weakens the locks for this session similarly like the option
innodb_locks_unsafe_for_binlog. This patch removes almost all
gap locking (used in next-key locking) and makes MySQL to release
the row locks on the rows which does not belong to result set.
Additionally, nonlocking selects on INSERT INTO SELECT,
UPDATE ... (SELECT ...), and CREATE ... SELECT ... use a
nonlocking consistent read. If a binlog is used, then binlog
format should be set to row based binloging to make the execution
of the complex SQL statements.