Qlik Replicate target Oracle database experienced a transient CPU spike per query UPDATE /*+ PARALLEL(tempview)

[wei_guo]

During Change Data Capture (CDC) replication, the target Oracle database experienced a transient CPU spike.

Database performance monitoring identified that the high CPU consumption was driven by the following automated bulk query generated by Qlik Replicate:

UPDATE /*+ PARALLEL(tempview) */ ( SELECT /*+ PARALLEL("CDC"."CATB_ENTRIES_DECOUPLING") PARALLEL("QLIK_TARGET"."attrep_changes69C66930_0000001") */ ...

The underlying cause of the resource spike was the execution of this query using aggressive Oracle PARALLEL hints, which exhausted available target DB CPU/memory resources.

Resolution

To prevent future resource contention and CPU/memory alerts in the target database, parallelism hints must be disabled or tuned within Qlik Replicate. This involves modifying two internal parameters across the Full Load and CDC stages: bulkUseParallel and directPathParallelLoad.

bulkUseParallel is for CDC / Change Processing and is enabled by default (true). It instructs Qlik Replicate to inject the Oracle PARALLEL hint into bulk DML statements for better target performance.

Setting it to false stops queries such as UPDATE /*+ PARALLEL(tempview) */ ... from executing in parallel, preventing CPU spikes.

This may cause a slight performance degradation during high-volume CDC processing.

directPathParallelLoad is for Full Load and enabled by default (true). It enables Direct Path loading using parallel processing only during the initial Full Load phase. It has no impact on the daily CDC.

Setting it to false proactively protects the DB during table reloads.

Will likely increase the time required to complete Full Load operations.

How to set the Internal Parameters in Qlik Replicate:

1. Navigate to Manage Endpoint Connection → Targets and select your Endpoint
2. Open the Advanced tab and select Internal Parameters
3. Add bulkUseParallel and directPathParallelLoad
4. Untick the Value checkbox to disable them
   
   
   
   
5. Click OK

Environment

• Qlik Replicate