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Problem IT35021
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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 / B10 - DB2 |
| Problem description: |
Db2 by default uses the 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 feature availability is predicated on Db2
license type, which is checked during index creation and
requires a 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 a
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 behavior by reducing the frequency of
license type checks. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* upgrade to 11.1.4.6 or higher *
**************************************************************** |
| Local Fix: |
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| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* upgrade to 11.1.4.6 or higher *
**************************************************************** |
| Comment |
upgrade to 11.1.4.6 or higher |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 23.11.2020
12.03.2021
12.03.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
