Data Change Notification performance impact

Question

I built a simple application that is monitoring Oracle's DB on a single table. I tried to test performance impact of enabled subscription and was unpleased surprised that degradation is about x2 for inserting about 10000 records each in standalone transaction.

• without subscription 10k insert ~ 30 sec
• with subscription ROWID granularity 10k insert ~ 60 sec

If I set:

OracleConnection.DCN_NOTIFY_ROWIDS, "false" OracleConnection.DCN_QUERY_CHANGE_NOTIFICATION, "false"

then all degradation is vanishing but I need to get details of updates. I removed all extra processing from client side so this is all about subscription overhead.

I am wondering is it so expensive by nature or I can tune this somehow?

Answer 1

Database change notification has an overhead during commit. This can't be tuned. Note that this feature is designed for read-mostly tables that are worth being cached on the client/mid-tier. One trick might be to unregister your app during batch inserts.