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HANA Delta Merge for unobstructive

Nov 21, 2016 at 01:34 PM

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Hi Folks,

I have gone through several threads since I have not found correspoding one...

We have setup a HANA platform for a critical high speed response activity. The database serves about 7 million customers. Out of the 7 million customers, status of about 1.5 million customers is regularly updated by a separate OLTP/source system. We have set the Delta Merge trigger to about 2 million records. Our concern is that we do not want a delayed response to customer queries if there is a query during a Delta Merge operation against the main table. So, my question is:

1.Can we schedule the Delta Merge only at a pre-scheduled time?

2.Will the table be available for responding to customer queries if it kicks in during the day?

3.We also do not want the incoming stream to be blocked during a delta merge.

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2 Answers

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Former Member
Nov 21, 2016 at 01:45 PM
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To put it very simply, don’t worry about it. HANA is a strong OLTP system being the platform of choice at SAP – S/4 HANA is an example, wherein multiple tables are regularly updated and increasingly mission-critical activities are being deployed on it.

1.Running at Pre-scheduled time :

  • Not as a standard functionality but as an implementation, YES.You can, of course, disable automatic delta merge for specific tables if you want by running :
ALTER TABLE TABLE_NAME {ENABLE | DISABLE}  AUTOMERGE
  • And then, schedule a job to run a manual delta merge at pre-schedule time with :
MERGE DELTA OF '(table_name)' WITH PARAMETERS ('FORCED_MERGE' = 'ON')

2 & 3 Responsive behavior & Incoming Stream blocking:

  • The table will very much be responsive – and incoming streams are not impacted at all.
  • The Delta store is not a static object in HANA. As soon as a Delta Merge operation kicks in, HANA provides and makes available a Secondary Delta store object for incoming streams.
  • The main table and the first delta object are still available to read-only queries but you cannot write to the first delta – that takes care of responsiveness to read queries.

You can find lot more details at:

https://help.sap.com/saphelp_hanaplatform/helpdata/en/bd/9ac728bb57101482b2ebfe243dcd7a/content.htm

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Amol Samte Nov 22, 2016 at 05:37 AM
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Dear Kapil,

Thanks for your early and prompt response.

I got the clarification regarding my question hence I am marking this answer as correct.

Thanks,

Amol Samte

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