Unlock Table Charter For Free

Table locks set within a transaction are released automatically when the transaction completes. If you are using an ANSI-compliant database, do not issue an UNLOCK TABLE statement. The UNLOCK TABLE statement fails if it is issued within a transaction, and a transaction is always in effect in an ANSI-compliant database.

InnoDB releases its internal table lock at the next commit, but for MySQL to release its table lock, you have to call UNLOCK TABLES . You should not have autocommit = 1 , because then InnoDB releases its internal table lock immediately after the call of LOCK TABLES , and deadlocks can very easily happen.

To change the lock mode of a table in a database that was created without transaction logging, use the UNLOCK TABLE statement to unlock the table, then issue a new LOCK TABLE statement.

To change the schema without locking a table, make sure that the original table contains a primary key or unique index. This allows you to copy all or part of data from the original table and synchronize incremental data. If the table contains only a primary key, make sure that the primary key is not updated.

Answer: The only way to release a lock on an Oracle table is to kill the session that is holding the lock, or wait for the transaction to complete. See my related notes on finding Oracle locked_objects and killing_Oracle sessions.

In MySQL, locked tables are identified using the SHOW OPEN TABLES command. In its simplest form is displays all locked tables. All open tables in the table cache are listed, but the IN_USE column indicates of the table is locked. When the first lock is taken, the value increments to 1.

A session releases all the tables locks with it at once. You can implicitly release the table locks. If the connection to the server terminates explicitly or implicitly all the locks will be released. You can release the locks of a table explicitly using the UNLOCK TABLES statement.