Connections associated with distributed transactions can become orphaned if the connection to the server is lost before the transaction has completed. When connections associated with distributed transactions are orphaned, any locks held by the database for that transaction are maintained, which can cause data to become unavailable. By cleaning up distributed transactions, connections associated with those transactions are freed and any locks held by the database are released.
You can use the XAResource.recover() method to clean up distributed transactions that have been prepared, but not committed or rolled back. Calling this method returns a list of active distributed transactions that have been prepared, but not committed or rolled back. An application can use the list returned by the XAResource.recover method to clean up those transactions by explicitly committing them or rolling them back. The list of transactions returned by the XAResource.recover method does not include transactions that are active and have not been prepared.
In addition, the SQL Server driver supports the following methods of distributed transaction cleanup.
Transaction timeout sets a timeout value that is used to audit active transactions. Any active transactions that have a life span greater than the specified timeout value are rolled back. Setting a transaction timeout allows distributed transactions to be cleaned up automatically based on the timeout value.
Explicit transaction cleanup allows you to explicitly roll back any transactions left in an unprepared state based on a transaction group identifier. Explicit transaction cleanup provides more control than transaction timeout over when distributed transactions are cleaned up.
Transaction timeout sets a timeout value that is used to audit active transactions. Any active transactions that have a life span greater than the specified timeout value are rolled back. Setting a transaction timeout allows distributed transactions to be cleaned up automatically based on the timeout value.
