|
Problem IC98144
|
Status: Closed |
LATCH PROTOCOL ISSUE IN ZIG ZAG JOIN EXECUTION LEADING TO DEADLATCH BETWEEN SUBAGENTS |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
This problem is similar to apar IC91168.
The problem will manifest itself as 2 subagents for one
statement deadlatching themselves on 2 internal latches.
This can easily be identified by running db2pd -latches which
may show :
db2pd -latches shows :
Latches:
Address Holder Waiter Filename
LOC LatchType HoldCount
0x0700000030CD7BD8 20049 20563 sqlpsvpt.C
207 SQLO_LT_SQLP_SAVEPOINTS__spLatch 1
0x07000000201F0128 20563 20049
/view/db2_v101fp2_aix64_s121127_special_30486/vbs/engn/include/s
qldinlines.h 8574 SQLO_LT_SQLD_APP_CB__inDMSlatch 1
The names of the latches : SQLO_LT_SQLP_SAVEPOINTS__spLatch and
SQLO_LT_SQLD_APP_CB__inDMSlatch are important here
and you will see that the holder and waiter are reversed for the
2 latches.
Collecting stack information via db2pd -stack all will show
these 2 subagents with the following stacks:
Subagent 1 is in sqldRowInsert requesting the inDMS latch,
holding the SavePoint latch.
getConflictComplex
getConflict
sqldRowInsert
sqlrinsr
sqlriisr
sqlriSectInvoke
Subagent 2 is in sqldBeginIndexCreate requesting the SavePoint
latch, holding the inDMS latch.
sqlpGetSPLatch
sqlpSpReq
sqldBeginIndexCreate
sqlriCreateTempTableIndex
sqlriCreateIndexedTempTable
sqlritib2
sqldDataFetch
sqliScanLeaf2NoLocking
sqlifnxt
sqlirdk
sqldIndexFetch
sqldRowFetch
sqlritaSimplePerm
sqlriZZOpenDims
sqlriZZInit
sqlriZigZagJoin |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 version 10.5.0.4. *
**************************************************************** |
| Local Fix: |
To avoid this problem, the usage of the Zig Zag join , join
strategy can be disabled by running :
db2set DB2_REDUCED_OPTIMIZATION="ZZJN OFF" |
| available fix packs: |
DB2 Cancun Release 10.5.0.4 (also known as Fix Pack 4) for Linux, UNIX, and Windows
DB2 Version 10.5 Fix Pack 9 for Linux, UNIX, and Windows
|
| Solution |
The problem is first fixed in DB2 version 10.5.0.4. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 05.12.2013
16.09.2014
16.09.2014 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.4
|
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