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Wednesday, January 27, 2016

Keep Shared Memory Over Restart in HANA



Here, I explained about parameter keep_shared_memory_over_restart which is related to shared memory and how it will work in the time of HANA database startup.

Parameter Name       - keep_shared_memory_over_restart
Default Value           - true
About Parameter      - Is set to true or false, if true the row store data will stay in shared memory.

How to Set Parameter - indexserver.ini -> [row_engine] -> keep_shared_memory_over_restart

If set to true, SAP HANA will keep the row store in memory when the technical preconditions are fulfilled. If set to false, the row store is generally recreated from scratch during a 
startup.

Note : If you run the following on the OS level ipcs -m to view the shared memory you will see the shared memory will have segments set to DEST status and do not go away, even after the HANA services are stopped (Soft shutdown). The reason for this is because the row store data is still in shared memory so that when your HANA services are restarted it won't have to reload the data.


Related Topic - Shared Memory Parameter in HANA

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