topic Re: Best approach for large, long running transactions in Qlik Replicate in Qlik Replicate

Best approach for large, long running transactions in Qlik Replicate

NakulanR — Wed, 06 May 2026 01:08:47 GMT

Hi Support,

In a scenario where it's known that a high volume, long running transaction is about to be committed in the source database, what approach should be taken in Replicate?

Should Replicate be kept running as per usual? Or is it better to have the task stopped whilst the transaction is open in the source and only resumed once the transaction has been committed in the source database? Or is there no difference between the 2 approaches.

Look forward to your insight on this

Thanks,
Nak

Re: Best approach for large, long running transactions in Qlik Replicate

john_wang — Wed, 06 May 2026 01:22:01 GMT

Hello Nak, @NakulanR

Good morning and thanks for the post here.

Short answer: The task should be kept running as normal.

The main objective is to allow Qlik Replicate to catch up with changes as quickly as possible. In most RDBMS platforms, Replicate can only capture committed changes, since changes become visible only after the transaction is committed. In some databases (e.g., Oracle and IBM DB2 LUW), Replicate can start reading changes from the logs even before the transaction commits.

By keeping the task running, Replicate can begin reading changes as soon as they are written to the logs. If the large transaction is eventually committed, the changes will be applied to the target. If it is rolled back, the changes will simply be discarded.

Pros of keeping the task running

Replicate continues reading logs without interruption
No restart or repositioning overhead
Faster catch-up once the transaction is committed

Comparison to stopping/resuming the task

Replicate stops reading logs, which may slightly reduce load on the source system
However, it introduces restart overhead and delays in catching up
Additional operational complexity and potential risks during resume

In summary, keeping the task running is generally the preferred and safer approach.

Hope this helps.

John.

Re: Best approach for large, long running transactions in Qlik Replicate

NakulanR — Wed, 06 May 2026 01:24:41 GMT

Thanks for the prompt response @john_wang. Thanks for clearing that up

Re: Best approach for large, long running transactions in Qlik Replicate

john_wang — Wed, 06 May 2026 01:26:54 GMT

Thank you for your support! Nak. @NakulanR

Re: Best approach for large, long running transactions in Qlik Replicate

DesmondWOO — Wed, 06 May 2026 01:52:29 GMT

Hi @NakulanR ,

What is the source endpoint? Unless the large transaction is causing significant resource constraints (e.g. CPU, Memory, I/O), I recommend letting the task keep running.

Regards,
Desmond