ss

Understanding the SCN values

• max_checkpoint_scn: This is the SCN value at which the last checkpoint was taken by the Capture process. The Capture process has its own check point schedule.

At the same time, the v$streams_capture view provides additional information about the Capture process SCN values. As a supplement to the above shown information, the v$log and v$archived_log will show the SCN numbers.

A glance at various SCN values helps the DBA monitor and keep tight control over the Streams performance issues, if any. Analysis of the time lags helps in monitoring latency levels between the creation of a transaction, flushing to the redo log file, enqueue of the event and the dequeue process.

In summary, from the dba_capture view, the following columns can be seen:

START_SCN
CAPTURED_SCN
APPLIED_SCN
FIRST_SCN 
MAX_CHECKPOINT_SCN
REQUIRED_CHECKPOINT_SCN

From the v$streams_capture view, the following columns can be seen: