This variable allows you to control which locks are released at the end of a
transaction. If this variable is set to "1", 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.