This configuration variable allows you to control which locks are released at the end of a transaction. If this variable is set to 1 (on, true, yes), then locks set using the READ statement that are not specifically released or replaced by extended transaction locks (for example, by a REWRITE) are held at the end of the transaction. Locks are released during a transaction by any operation that would ordinarily release them, unless those locks were replaced by extended transaction locks.

If TRX_HOLDS_LOCKS is set to the default, 0 (off, false, no), then locks are released at the end of a transaction, and the UNLOCK verb has no effect during a transaction.