Instantiation Requirements for DB2 LUW
During the initialization of the Oracle GoldenGate environment, you will be doing an initial data synchronization and starting the Oracle GoldenGate processes for the first time. In conjunction with those procedures, you will be creating process groups. To create an Extract group, an initial start position must be established in the transaction log. This initial read position is on a transaction boundary that is based on one of the following:
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End of the transaction file
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A specific LRI value
The start point is specified with the BEGIN option of the ADD EXTRACT command.
When the Extract process starts for the first time, it captures all the transaction data that it encounters after the specified start point, but none of the data that occurred before that point. This can cause partial transactions to be captured if open transactions span the start point.
To ensure initial transactional consistency:
To avoid the capture of partial transactions, initialize the Extract process at a point in time when the database is in a paused state. DB2 LUW provides a QUIESCE command for such a purpose. This is the only way to ensure transactional consistency.
Note:
After the Extract is past the initialization, subsequent restarts of the Extract do not extract partial transactions, because the process uses recovery checkpoints to mark its last read position.
To view open transactions:
IBM provides a utility called db2pd for monitoring DB2 databases and instances. You can use it to view information about open transactions and to determine if any of them span the start point. However, because DB2 LUW log records lack timestamps, it might not be possible to make an accurate assessment. If possible, quiesce the database prior to initialization of Oracle GoldenGate.