mysql5.1 disable index gap locking

With MySQL V5.0 or before, use the my.cnf option innodb_locks_unsafe_for_binlog to minimize next-key locking.This is safe only if you do not use binlogging for replication,OR, if your application is not prone to 'phantom row' problems

Beginning with MySQL-5.1.xx, if you use row-based replication, you can safely reduce next-key locking by setting innodb_locks_unsafe_for_binlog use TRANSACTION ISOLATION LEVEL READ COMMITTED.

the detail refer URL as following:

http://dev.mysql.com/doc/refman/5.1/en/innodb-parameters.html#sysvar_innodb_locks_unsafe_for_binlog