I replicate a lot of data to a central Oracle data location. A very large amount of redo logs are generated nightly with very large archived redo log files generated as well. We're looking for ways to reduce this amount.
Does replication generate a large amount of redo in the target Oracle database? If so, is there a way to turn off logging for this data or these schemas?
Yes. Qlik Replicate generates redo on the target Oracle database because it applies changes using standard INSERT/UPDATE/DELETE operations, and Oracle always writes redo for conventional DML. This means large replication loads can create very large online and archived redo logs on the target.
There is no supported way in Qlik Replicate to fully turn off redo logging per schema or table. Oracle’s NOLOGGING only reduces redo for direct-path operations (e.g., CTAS or INSERT /*+ APPEND */), but Qlik Replicate does not use direct-path inserts for CDC, so redo generation cannot be avoided during ongoing replication.
Regarding your observation about high redo log generation during nightly replication, the short answer is yes: Every INSERT, UPDATE, and DELETE operation applied to the target Oracle database is a standard transaction that must be recorded in the Redo Logs to ensure data integrity and recoverability.
Regarding CDC, as Sachin mentioned, Qlik Replicate performs standard DML statements. Since these are conventional inserts/updates, Oracle must generate redo logs to ensure ACID compliance and recoverability.
If the redo log volume is overwhelming during the Full Load phase, and you really don't need the redo log, you may try the internal parameter "directPathNoLog", provided that your environment is not using Active Data Guard.
Regards, Desmond
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Yes. Qlik Replicate generates redo on the target Oracle database because it applies changes using standard INSERT/UPDATE/DELETE operations, and Oracle always writes redo for conventional DML. This means large replication loads can create very large online and archived redo logs on the target.
There is no supported way in Qlik Replicate to fully turn off redo logging per schema or table. Oracle’s NOLOGGING only reduces redo for direct-path operations (e.g., CTAS or INSERT /*+ APPEND */), but Qlik Replicate does not use direct-path inserts for CDC, so redo generation cannot be avoided during ongoing replication.
