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Thursday, January 21, 2016

Performance Issue in hana Database



Case Study:

HANA DB Version : 97

Symptoms:

We are facing performance issues in SID Hana Database , Due to performance issue memory utilization in HANA database is reaching to threshold point .

Memory at H/W level : 1 TB
Hana Database  Size : 220 GB

Then DBA Finding's :

Below Finding from Index Server Trace file:

Total allocated memory = 1046594002944b (974.71gb)
Total used memory        = 1000702303849b (931.97gb)
Sum AB                         = 1029626544128
Sum Used                       = 983734845033
Heap memory fragmentation: 4

Top allocators (component, name, size). Ordered descending by inclusive_size_in_use.

 1: System:       /             977995705511b (910.82gb)
 2: System:     Pool         910542437746b (848gb)
 3: Statement Execution & Intermediate Results: Pool/JoinEvaluator    767792139088b (715.06gb)
 4: Statement Execution & Intermediate Results: Pool/JoinEvaluator/JECreateNTuple        472033054784b (439.61gb)
 5: Statement Execution & Intermediate Results: Pool/JoinEvaluator/NTuple   295569563952b (275.27gb)

In  above Trace , it clearly states JoinEvaluator  is the Top allocator so it mean Performance Issue in hana Database due to joins in query.

Solution :


1. This is a HANA bug which have seen in  SAP HANA version 97 .

Expected Fix:

Issue has been fixed in HANA version 102.4.

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