|
Problem IT34748
|
Status: Closed |
UPDATE STATEMENT SLOW PERFORMANCE CAUSED BY LATCH CONTENTION DURING THE MEMORY ALLOCATIONS.
|
| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
Poor update performance reported in db2WoC.
The cause for the slow performance was determined to be latch
contention during the memory allocations.
Special build fix:
This fix changes the memory pool for a memory allocation so that
there is much less latch contention.
Below is a sample of the stack trace that has the latch
conflicts on the UPDATE statement:
sample update statement:
>
UPDATE tab5 t5 SET col7 = t1.col7
FROM
tab1 t1,
tab2 t2
WHERE
t5.col1 = t1.col1
t2.change_dt = 'CUR_DATE' AND
t1.col3 = t2.col3;
Stack:
======
0x00007FCF5CA4A1D2 _ZN17SQLO_SLATCH_CAS6418getConflictComplexEm
+ 0x0672
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF5CB9730B _ZN13SQLO_MEM_POOL12captureLatchEv + 0x00db
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF5CB7D52D sqlofmblkEx + 0x029d
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF560E2D02 _ZN7ibm_cde8services4Heap7freeMemEPKcmPv +
0x02a2
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF5612CC05 _ZN7ibm_cde5types9BitStringD1Ev + 0x0035
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF561F2D89 _ZN7ibm_cde5types7TSNListD1Ev + 0x0059
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF56E288E3
_ZN7ibm_cde4data12TupleBuilder15loadColumnValueERKNS0_6ColumnENS
_5types3TSNERNS0_13TableAccessorERNS5_22TypeAllocatorResourcesEm
P10sqlz_value + 0x0113
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF56C3F393
_ZN7ibm_cde4data13TableAccessor19decomposedUpdateRowENS_5types3T
SNES3_PK18sqlriCdeColumnListS6_RNS0_17TableIndexUpdaterERNS2_9Bi
tStringERNS2_22TypeAllocatorResourcesERNS2_10SQLWarningEmP10SQLI
_IXPCR + 0x0853
(/head/home/db2inst1/sqllib/lib64/libdb2e.so.1)
0x00007FCF58806548
_ZN25cdeTableAccessorInterface19decomposedUpdateRowEmmPK18sqlriC
deColumnListS2_P26cdeDirectInsertTupleHandlelP10SQLI_IXPCR +
0x0128
Waiting on latch type: (SQLO_LT_SMemPool__MemLatchType__latch) -
Address: (0x7f8318d40540), Line: 318, File:
sqlo_mem_standard_pool.C |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 11.5.5.1 or higher *
**************************************************************** |
| Local Fix: |
N/A |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Db2 11.5.5.1 or higher *
**************************************************************** |
| Comment |
Upgrade to Db2 11.5.5.1 or higher |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 02.11.2020
31.03.2021
31.03.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
