Oracle7 Server Distributed Systems Volume II: Replicated Data

Diagnosing Problems with the Deferred Transaction Queue

When you call DBMS_DEFER_SYS.SCHEDULE_EXECUTION, Oracle adds this job to the job queue. If you have scheduled your transaction queue to be pushed at a periodic interval, and you encounter a problem, you should first be certain that you are not experiencing a problem with the job queue. For information on diagnosing job queue problems, see

When the symmetric replication facility pushes a deferred transaction to a remote site, it uses a distributed transaction to ensure that the transaction has been properly committed at the remote site before the transaction is removed from the queue at the local site.

For information on diagnosing problems with distributed transactions (two-phase commit), see Oracle7 Server Distributed Systems, Volume I.

If you notice that transactions are not being pushed to a given remote site, you may have a problem with how you have specified the destination for the transaction. If you specify a destination database when you call DBMS_DEFER_SYS.SCHEDULE_EXECUTION (using the DBLINK parameter), or DBMS_DEFER_SYS.EXECUTE using the DESTINATION parameter), you must provide the full database link. These procedures do not expand the database link name.

Having the wrong view definitions can lead to erroneous deferred transaction behavior. The DEFCALLDEST and DEFTRANDEST views are defined differently in CATDEFER.SQL and CATREPC.SQL. The definitions in CATREPC.SQL should be used whenever symmetric replication is used. If CATDEFER.SQL is ever (re)loaded, ensure that the view definitions in CATREPC.SQL are subsequently loaded.