|
Problem IT31248
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Status: Closed |
Under high concurrency, performance of queries using TEMP might be affected due to SQLO_LT_SQLB_PTBL__pool_table_latch latch
|
| product: |
DB2 FOR LUW / DB2FORLUW / B10 - DB2 |
| Problem description: |
On systems with a high concurrency of the queries using TEMP
operator (typically observed with SORT or CTEs) and where there
are more than one system temp tablespace for given page size a
performance degradation might be observed.
System will report:
- increased TOTAL_EXTENDED_LATCH_WAIT_TIME
- waits on SQLO_LT_SQLB_PTBL__pool_table_latch in
MON_GET_EXTENDED_LATCH_WAIT
- db2pd -latches showing EDUs waiting on
SQLO_LT_SQLB_PTBL__pool_table_latch
The response time of tablespace monitoring interfaces including
MON_GET_TABLESPACE and administrative views based on it will be
also affected.
A backtrace from Db2 engine collected during the slowness will
show threads with sqlbGetSysTempDatapool function on the top of
the stack, e.g:
SQLO_SLATCH_CAS64::getConflict
sqlbGetSysTempDatapool
sqldInternalCreateTable
sqldTableCreateTemp |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All Users on DB2 v11.1 *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to product DB2 v11.5. *
**************************************************************** |
| Local Fix: |
As a temporary workaround to this issue, drop all system managed
temp
tablespaces of the same page size leaving just one. |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* All Users on DB2 v11.1 *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to product DB2 v11.5. *
**************************************************************** |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 11.12.2019
18.02.2021
18.02.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
