Few doubts wrt Qlik replicate

[suvbin]

Hi, 

what if redo logs are deleted by mistake by DBA , how the replicate task will run
does full load needs archive redo logs ? how does it run?

ideally in  one task, how many tables can we set up?

How many tasks can one replicate server can have?

[Arun_Arasu · Accepted solution]

Hello @suvbin ,

Thank you for contacting Qlik Support.

Regarding the issue you mentioned, we recommend checking the following article for assistance: https://community.qlik.com/t5/Official-Support-Articles/Replicate-using-Oracle-source-fails-with-mis...

In simple terms, if you have deleted the archive logs and cannot restore them, performing a full load is the only viable option.

For your additional question:

• The number of tasks that one Replicate server can have depends on the source architecture.

For more details on the limitations per server in terms of tasks and tables, please refer to this article: 

https://community.qlik.com/t5/Qlik-Replicate/Qlik-Replicate-number-of-tasks-and-table-limitation-per....

If you have any further questions or need additional support, feel free to ask.

Best regards,

Arun

[suvbin]

Thank you arun for your quick response. 

--> does full load needs archive redo logs ? if not...  behind the scenes how does it runs ? 

[DesmondWOO]

Hi @suvbin ,

Regarding this questoin,

"What if redo logs are deleted by mistake by DBA, how the replicate task will run does full load needs archive redo logs? how does it run?"

> Full Load means that Replicate transfers all your data from the source table to the target table, without requiring redo logs. If your task setting is Full Load and CDC (Apply changes/Store changes), Replicate will perform a full load while simultaneously starting to capture changes from the redo log.

Regards,
Desmond

[Arun_Arasu]

Hello @suvbin ,

When it comes to database replication, two primary methods are commonly used: Full Load and Change Data Capture (CDC). Each method serves a distinct purpose and understanding the difference between them is essential for efficiently managing data replication processes.

Full Load:
Full Load is a comprehensive data replication technique that doesn't require archived logs. During a Full Load, the entire dataset from the source database table is extracted and copied to the target database. This process is akin to executing a simple SQL query like "SELECT * FROM table." It's commonly used when initializing the replication process or when there have been significant changes to the source data structure.

Change Data Capture (CDC):
CDC is a more efficient approach that captures only the changes made to the source database since the last replication cycle. It relies on archived logs to track insert, update, and delete operations on the source database. By capturing these changes, CDC ensures that only relevant modifications are propagated to the target database, minimizing the replication time and resource consumption.

In conclusion, both Full Load and CDC play crucial roles in database replication strategies. The Full Load method is employed for the initial synchronization or significant data changes, while CDC excels at efficiently capturing incremental changes for real-time synchronization.

Below are some reference article which will give you more insight

https://community.qlik.com/t5/Official-Support-Articles/An-Introduction-to-Qlik-Replicate-Tasks-Full....

https://help.qlik.com/en-US/replicate/May2022/Content/Replicate/Main/Introduction/FullCDCProcesses.h...

We hope the above was helpful and remain at your disposal for any other questions, doubts or concerns you may have.

Thanks & Regards,

Arun

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[shashi_holla · Accepted solution]

@suvbin 

Just to circle back on the 2 questions you had as I was not sure if we answered them:

ideally in one task, how many tables can we set up?

Replicate doesn't have any limit on number of tables we can have on a task, but it's not recommended to go beyond 1000 to avoid maintenance difficulties.

How many tasks can one replicate server can have?

It's recommended to not have more than 100 tasks in one Replicate server.

Thank you,