|
Problem IC95295
|
Status: Closed |
QUERY WITH TABLESAMPLE SYSTEM() MIGHT HANG IN SMP MODE (INTRA_PARALLEL = YES) |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
A query with TABLESAMPLE SYSTEM() might hang if it runs in
parallel mode, i.e. INTRA_PARALLEL = YES.
This issue was observed with ADMIN_MOVE_TABLE function which
might use such queries starting with DB2 v10.1 Fixpack 1 (see
also APAR IC84414).
You might see a query like the following when executed with sub
agents to hang:
SELECT ...
FROM <table> TABLESAMPLE SYSTEM() WITH UR;
A stack trace against the coordinating agent might show
"sqkfChannel::WaitRecvReady" function waiting to receive data
from sub agents:
ossDumpStackTraceInternal
ossDumpStackTrace
OSSTrapFile::dumpEx
sqlo_trce
sqloDumpDiagInfoHandler
semtimedop
sqloWaitEDUWaitPost
sqkfChannel::WaitRecvReady
sqkfChannel
sqlkqrcv
sqlktrcv
sqlkt_unpack_tuple
sqlktftc
sqlritqa
sqlriSectInvoke
sqlrr_process_fetch_request
sqlrr_open
sqljs_ddm_opnqry
sqljsParseRdbAccessed
...
but in application snapshot there are no associated sub agents
anymore. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* ALL *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 Version 10.5 Fixpack 1 *
**************************************************************** |
| Local Fix: |
Do not use INTRA_PARALLEL, or turn parallelism off for the
query, i.e.: SET CURRENT DEGREE = '1' |
| available fix packs: |
DB2 Version 10.5 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 10.5 Fix Pack 3a for Linux, UNIX, and Windows
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 |
Problem was first fixed in DB2 Version 10.5 Fixpack 1 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.08.2013
18.09.2013
18.09.2013 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
