JTA Functionality in TimesTen

TimesTen Database Requirements for XA

To guarantee global transaction consistency, TimesTen XA transaction branches must be durable.

The TimesTen implementation of the xa_prepare(), xa_rollback(), and xa_commit() functions log their actions to the file system, regardless of the value set in the DurableCommits general connection attribute or by the ttDurableCommit built-in procedure. If you must recover from a failure, both the resource manager and the TimesTen transaction manager have a consistent view of which transaction branches were active in a prepared state at the time of failure.

Global Transaction Recovery in TimesTen

When a database is loaded from the file system to recover after a failure or unexpected termination, any global transactions that were prepared but not committed are left pending, or in doubt. Processing is not enabled until the disposition of all in-doubt transactions has been resolved.

After connection and recovery are complete, TimesTen checks for in-doubt transactions. If there are no in-doubt transactions, operations can proceed. If there are in-doubt transactions, other connections may be created, but virtually all operations are prohibited on those connections until the in-doubt transactions are resolved. Any other JDBC calls result in the following error:

Error 11035 - "In-doubt transactions awaiting resolution in recovery must be 
resolved first"

The list of in-doubt transactions can be retrieved through the XA implementation of xa_recover(), then dealt with through the XA call xa_commit(), xa_rollback(), or xa_forget(), as appropriate. After all the in-doubt transactions are cleared, operations can proceed.

This scheme should be adequate for systems that operate strictly under control of the transaction manager, since the first thing the transaction manager should do after connect is to call xa_recover().

If the transaction manager is unavailable or cannot resolve an in-doubt transaction, you can use the ttXactAdmin utility -HCommit or -HAbort option to independently commit or roll back the individual transaction branches. Be aware, however, that these ttXactAdmin options require ADMIN privilege. See ttXactAdmin in Oracle TimesTen In-Memory Database Reference.

XA Error Handling in TimesTen

The XA specification has a limited, strictly defined set of errors that can be returned from XA interface calls. The ODBC SQLError mechanism returns XA defined errors, along with any additional information.

The TimesTen XA related errors begin at number 11000. Errors 11002 through 11020 correspond to the errors defined by the XA standard.

See Errors and Warnings in Oracle TimesTen In-Memory Database Error Messages and SNMP Traps.