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Problem IT35082
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Status: Closed |
High CPU and decreased performance with high concurrency of index creation (on TEMP TABLES)
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| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
Db2 by default uses compression for indexes on created/declared
temporary tables (CGTTs/DGTTs) and this behavior cannot be
explicitly disabled, that is, there is no possibility to use
"COMPRESS NO" keyword.
Index compression entitlement is checked during index creation
and requires serialization via a latch (mutex).
If indexes are created with a very high concurrency the
performance of that operation can be affected and CPU usage on
the system will increase. This typically happens with scenarios
involving indexes on declared/created temporary tables that have
indexes defined.
A backtrace of Db2 engine threads (EDUs) collected during the
issue with a debugger/profiler or "db2pd -stack" will show a
call stack with the following functions near the top:
ossLockGetConflict
NetlsRequestLicense
LicGetAccessKey
sqllcRequestAccess
sqloSqlcRequestAccess
sqloLicRequestAccess
sqldIndexType
sqldIndexCreate
sqlrlRecreateSingleIndex
sqlrlRecreateIndexObject
sqlrlRecreateIndexes
This APAR will address the behaviour by removing the license
check for index compression on temporary tables. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5.6 *
**************************************************************** |
| Local Fix: |
|
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5.6 *
**************************************************************** |
| Comment |
Upgrade to 11.5.6 |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.11.2020
11.06.2021
11.06.2021 |
| Problem solved at the following versions (IBM BugInfos) |
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| Problem solved according to the fixlist(s) of the following version(s) |
