Qlik Fix: How to Restart a Qlik Replicate Task from LSN for a PostgreSQL Source

[Troy_Raney]

This video is part of the Qlik Fix Video series. If you found this video useful, check out the other Qlik Fix Videos.

Environment

• Qlik Replicate

This video demonstrates how to Restart a Qlik Replicate task from the Log Sequence Number or LSN for a Postgres source.

Attached is a downloadable .mp4 video file for those who cannot view YouTube videos.

Transcript

Hi and Welcome to Qlik Fix
This video will demonstrate how to Restart a Replicate task from the Log Sequence Number or LSN for a Postgres source.
Here we have sample task with one table which has Full load and Change Data Capture enabled.
We have a postgres source and a file target.
We’re replicating once table called C-sub test.
The task is currently stopped and has already gone through a full load.

Here’s how the table looks via PGadmin on the source side.
The UserID field currently runs up to 1433.
These inserts here will bump those values up once run
However those changes are not replicating to our target file because the task is not running.
Now to demonstrate how to restart the task using LSN for the postgres source.
Restarting the task using LSN for the postgres source can be a useful method if there are issues or limitations using the Resume processing option.
Using the Advanced Run Options will allow you to go back in time and reprocess records from the past without running a full load.
Under advanced options, we want the second choice.
Unfortunately, for a postgres source, restart from a date and time is not supported.
So, we will specify the LSN start position in the source database log
where you would like to resume change processing.
There are two ways to find this position value
Query
From Replicate log
Under Advanced Run Option in the Qlik Help documentation, there are some example queries to run to get the current LSN value in the source Database.
The second option is to get that value from the Replicate log file.
The logs can be found here under Program Files > Attunity > Replicate > Data > Logs
Ours is the most recent.
In the log file for the task, search for “Final saved task state"
After the words Stream Position is the LSN value that we’re looking for. Starting the replicate task from this position will pick up the changes that have occurred since the task was stopped.
Copy that.
Paste that value from the log in the Source Change position, then click okay
That task starts running again and it picked up those 2 inserts that were made after the task was stopped.
Those changes can even be confirmed in new change data capture log
Additionally, the task log confirms that the change data capture was initiated at the specified position, without performing a full load.
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Thanks for watching.

Nailed it!