Fixed a bug: the InnoDB range estimator greatly exaggerated the size of a short index range if the paths to the endpoints of the range in the index tree happened to branch in the root. This could cause unnecessary table scans in SQL queries.

Fixed a bug: ORDER BY could fail if you had not created a primary key to a table, but had defined several indexes of which at least one was a UNIQUE index with all its columns declared as NOT NULL.

Fixed a bug: a lock wait timeout in connection with ON DELETE CASCADE could cause corruption in indexes.

Fixed a bug: If a SELECT was done with a unique key from a primary index, and the search matched to a delete-marked record, InnoDB could erroneously return the NEXT record.

Fixed a bug introduced in 3.23.53: LOCK TABLES ... READ LOCAL should not set row locks on the rows read. This caused deadlocks and lock wait timeouts in mysqldump.

Fixed a bug: If an index contains some column twice, and that column is updated, the table becomes corrupt. From now on InnoDB prevents creation of such indexes.