1. Oracle GoldenGate Classic Documentation
  2. Administer
  3. Performing Administrative Operations
  4. Administering a Coordinated Replicat Configuration
  5. Recovering Replicat After an Unplanned Re-partitioning
  6. Reprocessing From the Low Watermark with HANDLECOLLISIONS

Reprocessing From the Low Watermark with HANDLECOLLISIONS

In this procedure, you reposition all of the threads to the low watermark position. This is the earliest checkpoint position performed among all of the threads. To state it another way, the low watermark position is the last record processed by the slowest thread before the unclean stop. When you start Replicat, the threads reprocess the operations that they were processing before Replicat stopped, and the HANDLECOLLISIONS parameter handles any duplicate-record and missing-record errors that occur as the faster threads reprocess operations that they applied before the unclean stop.

  1. Add the HANDLECOLLISIONS parameter to the Replicat parameter file. It is not necessary to use any THREADS options.
  2. Issue the INFO REPLICAT command for the Replicat group as a whole (the coordinator thread). Make a record of the RBA of the checkpoint. This is the low watermark value. This output also shows you the active thread IDs under the Group Name column. Make a record of these, as well.
    INFO REPLICAT group

GGSCI (slc03jgo) 3> info ra detailREPLICAT   RA       Last Started 2013-05-01 14:15   Status ABENDEDCOORDINATED          Coordinator                      MAXTHREADS 15Checkpoint Lag       00:00:00 (updated 00:00:07 ago)Process ID           11445Log Read Checkpoint  File ./dirdat/withMaxTransOp/bg000000001                     2013-05-02 07:49:45.975662  RBA 44704Lowest Log BSN value: (requires database login)Active Threads: ID  Group Name PID   Status   Lag at Chkpt  Time Since Chkpt1   RA001     11454 ABENDED  00:00:00      00:00:01    2   RA002     11455 ABENDED  00:00:00      00:00:04    3   RA003     11456 ABENDED  00:00:00      00:00:01    5   RA005     11457 ABENDED  00:00:00      00:00:02    6   RA006     11458 ABENDED  00:00:00      00:00:04    7   RA007     11459 ABENDED  00:00:00      00:00:04
  3. Issue the INFO REPLICAT command for each processing thread ID and record the RBA position of each thread. Make a note of the highest RBA. This is the high watermark of the Replicat group.
    INFO REPLICAT threadID

 info ra002
REPLICAT   RA002    Last Started 2013-05-01 14:15   Status ABENDEDCOORDINATED          Replicat Thread                  Thread 2Checkpoint Lag       00:00:00 (updated 00:00:06 ago)Process ID           11455
Log Read Checkpoint  File ./dirdat/withMaxTransOp/bg000000001                     2013-05-02 07:49:15.837271  RBA 45603
  4. Issue the ALTER REPLICAT command for the coordinator thread (Replicat as a whole, without any thread ID) and position to the low watermark RBA that you recorded.
    ALTER REPLICAT group EXTRBA low_watermark_rba
  5. Start Replicat.
    START REPLICAT group
  6. Issue the basic INFO REPLICAT command until it shows an RBA that is higher than the high watermark that you recorded. HANDLECOLLISIONS handles any collisions that occur due to previously applied transactions.
    INFO REPLICAT group
  7. Stop Replicat.
    STOP REPLICAT group
  8. Remove or comment out the HANDLECOLLISIONS parameter.
  9. Start Replicat.
    START REPLICAT group