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Aug 04 at 05:24 PM

Delta Mechanism Type CALDAY for Generic Extractor

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Hi All,

I am a SAP BW Consultant, currently working on a project and there is a possible requirements to create generic datasource/ extractor for several table. Here, I just want to ask, whether the information that I share is proper to be sharing knowledge or there is still some not correct information which need to be corrected and I also want to ask some question about this topic.

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So, the case is, I have a table with column AUFNR as a key, and two date columns, they are CREATE_DATE and CHANGE_DATE. As you can see in the picture attached, Create Day's column just to show when the Order Number is created and not one of the table's containing column. Let's suggest that the initialization was done on 01.01.2022 and normally there is two data records added to the generic extractor table. My concern show up, that is to pick CHANGE_DATE as delta type for CALDAY rather than pick CREATE_DATE.

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This is the explanation that I want to confirm :

delta-mechanism-generic-ds-calday.jpg

In the picture above, let's suggest, I pick CREATE_DATE as delta, on 06.01.2022, then, when delta on that day is running, 1 delta record was not fetched. The record is :

image.png

That is because the CREATE_DATE value 01.01.2022 as delta, so in the generic extractor table has the data with that same CREATE_DATE, when the initialization on 01.01.2022 was done and that record was mark as not delta, but we know that is wrong.

For avoid that kind of mistake, I prefer use the most update date column for become the delta, in this case, column CHANGE_DATE. As you can see, when delta is running on 06.01.2022, the delta record with CHANGE_DATE = 05.01.2022 was fetched.

Why delta on 06.01.2022 only fetch CHANGE_DATE = 05.01.2022 ? This is because, the setting I've used :

image.png

*Delta will fetch data from 2 days ago, but exclude today's data (curr. date), e.g. current date is 06.01.2022, so the delta will fetch data from 04.01.2022 to 05.01.2022.

For delta on 07.01.2022 only fetch data record for CHANGE_DATE = 06.01.2022, because CHANGE_DATE = 05.01.2022 data record was fetched on 06.01.2022 delta running.

For the explanation above, please tell me if there is still some incorrect information.

Now, we can move to some question from mine, they are :

1) The question is why SAP provide Lower and Upper Limit for generic extractor delta's mechanism ?

What I think is the Lower and Upper Limit act as delta data record's recover when the process chain error. For example, we have process chain that running on several days. For further detail, we can see picture below :

image.png

If the process chain on 02.02.2022 until 04.02.2022 was error, the process chain on 05.02.2022 can still fetch the delta from date 02.02.2022 and will sure get the delta if process chain on 05.02.2022 is finished succesfully.

2) What happen if I set Lowet Limit = 2 and Upper Limit = 1, with example current date 05.01.2022 ?

image.png

Whether there will be an intersection between Lower and Upper Limit? If yes, in this case that is useless, because we can just use Upper Limit = 1 and leave Lower Limit = <Blank> instead and still get the same result.

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Please tell me the answer and feel free to correct the information I have given. Thanks for put on some time for seeing this post, hope you have a great day!

Best Regards,

Clement A. S.

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