topic Re: If Replicate table use nologging option, is it no problem when replicate ? in Qlik Replicate

If Replicate table use nologging option, is it no problem when replicate ?

khchoy — Mon, 10 Aug 2020 03:16:32 GMT

Hi All,

If replicate table use nologging option (but table use supplemental log pk ), is it no problem ?

(this environment is Oracle source)

Customer ask me that they did not change to logging option after table reorganization. But replicate task did not met error and target data seems no problem.

So customer ask , Is "table logging option" not a mandatory condition ?

if it is a mandatory condition, why Qlik Replicate not show error message ?

Regards,

Kwang Ho

Re: If Replicate table use nologging option, is it no problem when replicate ?

Madhavi_Konda — Thu, 10 Sep 2020 14:42:14 GMT

Hi,
Did you check if force logging is enabled on database level or tablespace level?
Force logging at database and tablespace level will override nologging on table level.

Thanks,
Madhavi

Re: If Replicate table use nologging option, is it no problem when replicate ?

john_wang — Fri, 09 Oct 2020 14:36:10 GMT

Hello KwangHo,

It looks the NOLOGGING parameter is a little confusing and depends on the type of DML being done, we found the following here:

https://asktom.oracle.com/pls/apex/f?p=100:11:::NO:RP:P11_QUESTION_ID:5280714813869

As the AskTom article shows, 'nologging' does not mean there is, eh, no logging. Only when doing 'append' type of operations logging can be disabled. (or things like 'alter table move' or partition operations that juggle with whole segments)

So, if nologging is set on a table and you do 'direct load' inserts or inserts with an append hint, it might not be logged and Replicate will not see the changes. So regular DML *is* always logged and will always be noticed and replicated by Replicate.

It might be an omission in our documentation, on the other hand, I (personal opinion) think customers might want to think once or twice about what they do (the same article states that you should not leave 'nologging' on in a production database).

Let me summarize the jobs we did here:

1. Qlik Replicate cannot check everything in the table level or DB level, I do not think we need change QR; Simply because there is no such thing to 'support' it..

2. Customers should be aware of what they have done. They should not leave 'nologging' on in a production database or tables;

3. Some basic/simple test with NOLOGGING seems looks fine with Replicate but it cannot tell us we can keep NOLOOGING in PROD system.

Hope this helps.

Regards,

John.