column store error: [2465] not enough merge tokens for delta merge

[Former Member]

Hello All,

In HANA, from last many days I'm getting Alert ID 88: 'Alert Auto Merge for Column-Store Tables'

Alert: Delta Merge was not executed successfully for table USR02 in schema SAPXXX for 2 occurrences in the lst 24 hours.

User Action: The delta merge was not executed successfully for a table. Check the error description in view M_DELTA_MERGE_STATISTICS and also Indexserver trace.

When I have checked the view M_DELTA_MERGE_STATISTICS and found the error description as -

column store error: [2465] not enough merge tokens for delta merge

I'm encountering the issue for the first time and I could not find anything in SCN, SAP Note to deal with the above error.

I could not find anything in indexserver trace file. If any one has ever encountered the above issue, kindly let help me.

Note - Yes, I can forcefully run the table merge using below command, but before that I want to understand what issue exactly this is and why it is coming.

MERGE DELTA OF TABLE-NAME WITH PARAMETERS ('FORCED_MERGE' = 'ON');

Thanks & Regards,

Dennis Padia.

[former_member182967 · Accepted solution]

Hi Dennis,

Check if note 2351926 - Many "Delta Merge was not executed successfully" Alerts For Secondary Site helps or not.

Regards,

Ning

[Former Member · Accepted solution]

Hello Ning,

We have HANA Revision 112.03 and as workaround they have mentioned to set below parameter on secondary site with Note "It is important that the workaround is reverted before doing a takeover as this configuration can lead to an unexpected behaviour if it is set on primary site!"

As a workaround the number of merge tokens can be increased on secondary side by adding the following parameter to the configuration file "indexserver.ini" on secondary site:

[mergedog]
load_balancing_func = 1 + LCC

Afterwards you have to run the following command on secondary site as <sid>adm user:

hdbnsutil -reconfig

We have cluster setup for our system replication for automated failover, if the above parameters are being set on secondary site and due to some issue failover happens than secondary site will become primary and this parameter will create problem then. So do you have any idea how to handle.

Thanks & Regards,

Dennis Padia.

[former_member182967 · Accepted solution]

Hi Dennis,

For automatic failover configuration, it is better to directly update to rev.112.06 as it is released already.

Regards,

Ning

[Former Member]

Hello Dennis,

Have a look at the following note which describes error 2465 and what you can do to check. As per the note the error isn't critical.

2057046 - FAQ: SAP HANA Delta Merges

https://launchpad.support.sap.com/#/notes/2057046/E

KR,

Amerjit

[Former Member]

Hello Amerjit,

Thank you for the response. Yes I have checked the SAP Note and executed the SQL statement mentioned and it is showing me "Only available SAP internally, see internal SAP Note 2082221." Query has not been released to customer as well as the SAP Note which has been addressed in the query result.

Description mentioned in SAP Note -

This error is issued if during recovery a merge isn't able to proceed due to a lack of merge tokens. This can e.g. happen in system replication environments (SAP Note 1999880) with a configured logreplay replication mode.

You can use SQL: "HANA_Tables_ColumnStore_Merges_TokenOwners_Internal" (SAP Note 1969700) to understand which activities occupy how many merge tokens.

Normally this error isn't critical because a merge will be repeated at a later time when the current number of tokens is not sufficient.

Do you have any idea on how to find out the number of tokens and ways to control it, so avoid this issue.

Thanks & Regards,

Dennis Padia.