Advanced Run Options from Date/Time, which logs does Qlik Replicate Utilize for this in SQL Server?

[ksheets]

We have SQL Server and CDC (necessary due to SQL DAGs) we are utilizing in conjunction with Qlik Replicate and we have recently been exploring the Advanced Run Options from Date/Time to look at potentially pulling in missing data if the job errors and the database has been restored; instead of reloading in instances where the target tables already contain data. Which log files does Qlik utilize to determine this Point in time in SQL server? The documentation describes a Purge Policy and how it functions if the logs are not found, but doesn't go into detail about which logs it is utilizing. Any additional information would be appreciated on this topic.

[Dana_Baldwin]

Hi @ksheets 

Qlik Replicate reads from either the online source transaction log or the backup transaction logs. When you start from a timestamp, the application queries the source database to convert the timestamp to an LSN which it then determines which transaction log it resides in. Typically when starting from an earlier date/timestamp the task will be attempting to read from backup transaction logs. Depending upon how long those files are retained on disk could limit how far back you can go. Of course if you have the backup transaction logs stores on other media you can restore those to the disk drive to extend this - but please note you will need that backup transaction log and ALL subsequent logs to process CDC data up to the current time.

Hope this helps!

Dana

[zacker20]

Hey @Dana_Baldwin in CDC mode does it read from transaction logs?   We were told Qlik Replicate is unable to read transaction logs when we have a DAG (Distributed Availability Group).  

[Dana_Baldwin]

Hi @zacker20 ,

I apologize & thanks for the clarification. Upon checking the User Guide, I found that:

• DAG (Distributed Availability Groups) is not supported.

Working with Microsoft SQL Server AlwaysOn Availability Groups | Qlik Replicate Help

I do not know if this is on our roadmap to be able to support. The best option would probably be to engage our pre-sales team or your sales rep to look into a POC to see what options are available.

Thanks,

Dana

cc: @ksheets 

[zacker20]

Hey @Dana_Baldwin ,

So what does the option do when we are using CDC?

It seems to pull data when we use that option.  

[Dana_Baldwin]

Hi @zacker20 ,

Far as I know it would still be reading from the TLOG or backup TLOG, but if you could provide a task log with Source_Capture set to Trace to confirm that would help. If you do not want to post the log here, please open a support case.

Thanks,

Dana