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3298933 - Why does the user-specific statement memory limit not work even though it is set correctly in SAP HANA?

Symptom

Prerequisites:

  • You have setup the user-specific statement memory limit properly based on documentation: SAP HANA Troubleshooting and Performance Analysis Guide - Setting a Memory Limit for SQL Statements.
  • You already checked the setup with statement: SELECT * FROM USER_PARAMETERS.
  • Probably you are not using the latest version of the documentation.

Observation:

  • You recognize, even if the user-specific statement memory limit (e.g. 500 GB) is higher than the global limit (e.g. 250 GB) you receive OOM dump with the global limit value.
  • A composite-limit violation occurs at a value, lower than the value set in the user-specific statement memory limit (exactly happens on global limit value). 
  • You observed that the given limit does not take effect.

Trace (belongs to the above mentioned situation):

     [0]\{0\}[0/0] 2023-01-01 10:00:00.000000 e Memory           mmReportMemoryProblems.cpp(01834) : Composite limit violation (OUT OF MEMORY) occurred.
     Composite limit=250gb (268435456000b)
     Root allocator name=Connection/100000/Statement/1111111111111111
     Host: 
     Executable: hdbxsengine
     PID: 3333333
     Failed to allocate 94.19gb (101141883072b).

Note: There is a same issue happens when you set user-specific statement memory limit to a lower value than the global limit. The restriction does not come into effect in this case either. You checked the execution with statement: SELECT * FROM M_EXPENSIVE_STATEMENTS, and found the user specific limitation does not working.


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Environment

SAP HANA, platform edition 2.0

Product

SAP HANA, platform edition 2.0

Keywords

user, specific, user-specific, statement_memory_limit, statement, memory, limit, cross-database, cross, database, query, queries, OOM, composite, limit, violation, SAP, HANA, USER_PARAMETERS, M_EXPENSIVE_STATEMENTS, webide, web, ide, xs, xsc, classic, workload class , KBA , HAN-DB , SAP HANA Database , HAN-DB-ENG , SAP HANA DB Engines , Problem

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