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How does Replicate handle changes to source during a Full Load?

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KellyHobson
Support
Support

How does Replicate handle changes to source during a Full Load?

Last Update:

May 19, 2022 3:04:39 AM

Updated By:

Sonja_Bauernfeind

Created date:

May 18, 2022 9:49:06 AM

During a Replicate Full Load, incoming changes occur while the Full load is in progress. What happens to those changes?

Qlik replicate starts the CDC thread before starting the Full load and all the changes show as cached events while the Full load is running. For example, 2 billion records are applied in the Full load state and Replicate again check at the end of the Full load for committed changes.  If 100k changes are also committed before finished then it will also be applied in the full load otherwise the 100k changes will go to CDC.

Another example, for a full load takes 12 hours, then updates during the 12 hours full load window are also applied. Note- these two examples assume you have CDC enabled in the task.

If CDC is turned off during a full load task, then Replicate will not capture the cached events.

 

Environment

 

The information in this article is provided as-is and to be used at own discretion. Depending on tool(s) used, customization(s), and/or other factors ongoing support on the solution below may not be provided by Qlik Support.

 

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Comments
pedrobergo
Employee
Employee

Hi @KellyHobson,

I think these phrases are conflitant:

"If CDC is turned off during a full load task, then Replicate will not capture the cached events.

Another example, for a full load takes 12 hours, then updates during the 12 hours full load window are also applied."

In my experience and all of my tests, when using a FL Only task , there is no way to load any source change to the targets after task starts. So the second phrase will be correct only if Apply Changes or Store Changes are turned on.

Can you clarify it, please?

 

KellyHobson
Support
Support

Hey @pedrobergo ,

Thank you for the feedback! I have updated the article. Let me know if you think it needs further clarification.

Best,

Kelly

vasantskr
Contributor
Contributor

In what cases the cached events are missed to load into the target?

I am encountering a scenario where the cached events during the full load window do not appear in the target DB. The CDC followed by full load just works fine. The log file says, "the lob is not enabled in the task and one of the incoming columns will be converted to LOB". It is just an information not an error in the log. And it affects only the cached events.  

Version history
Last update:
‎2022-05-19 03:04 AM
Updated by: