Informix - Problem description
Problem IT16177 | Status: Closed |
RUNNING UPDATE STATISTICS LOW WITH USTLOW_SAMPLE ENABLED WILL CRASH SERVER IF DATA SKEW FOUND WITH "THREAD EXITED WITH # BUFFERS | |
product: | |
INFORMIX SERVER / 5725A3900 / C10 - IDS 12.10 | |
Problem description: | |
Running Update Statistics Low with USTLOW_SAMPLE enabled will crash the engine when exiting with "Thread exited with # buffers held", if on a big index data skew is found. You'll get a warning in the online.log about the inaccurate index statistics. 13:30:51 Warning: update statistics low using sampling may generate inaccurate index statistics for index informix.xxxxxx due to data skew 14:54:40 14:54:40 IBM Informix Dynamic Server Version 12.10.FC6X5WE Software Serial Number AAA#B000000 14:54:40 Assert Failed: Thread exited with 2 buffers held. 14:54:40 Who: Session(193, informix@xxxxxxx, 19844, 0x4db7a550) Thread(227, sqlexec, 4db3dde8, 1) File: rsshmem.c Line: 2083 14:54:40 Results: Dynamic Server must abort 14:54:40 SHM Globals and Master Pool/Master Block Adresses: 14:54:40 shmcb = 0x000000004419dc28 14:54:40 rhead = 0x000000004420a800 14:54:40 pool list = 0x000000004419dd00 14:54:40 block pool list = 0x0000000044204908 14:54:40 TRANSP = 0x000000004db7a550 14:54:40 PARTP = 0x0000000000000000 14:54:40 PARTNP = 0x0000000000000000 14:54:40 OPENP = 0x000000004f1d9828 14:54:40 FILEP = 0x000000004f1dd4e0 14:54:40 Raw hex dump of stack located in /opt/informix/tmp/af.4cbedff.rawstk 14:54:40 Stack for thread: 227 sqlexec base: 0x000000004f1f4000 len: 69632 pc: 0x00000000013f50e7 tos: 0x000000004f202b50 state: running vp: 1 (/opt/informix/bin/oninit) afstack (/opt/informix/bin/oninit) afhandler (/opt/informix/bin/oninit) afcrash_interface (/opt/informix/bin/oninit) rstcb_cleanup (/opt/informix/bin/oninit) destroy_session (/opt/informix/bin/oninit) sq_exit (/opt/informix/bin/oninit) sqmain (/opt/informix/bin/oninit) spawn_thread (/opt/informix/bin/oninit) th_init_initgls 0x000000000144e858 (/opt/informix/bin/oninit) startup Onstat -b shows: ===========------------- - - - - - - /opt/informix/bin/onstat -b: IBM Informix Dynamic Server Version 12.10.FC6X5WE -- On-Line -- Up 03:18:23 -- 3573872 Kbytes Buffers address userthread flgs pagenum memaddr nslots pgflgs xflgs owner waitlist Buffer pool page size: 2048 71a972d8 0 802 5:3432386 7e954000 0 2890 10 0 0 7ade6598 0 802 5:6639819 f46e3000 22 890 10 0 0 45 modified, 1310720 total, 2097152 hash buckets, 2048 buffer size and those pagenum belongs to index(es) for table reported, including the index reported on the warning. | |
Problem Summary: | |
Local Fix: | |
Solution | |
Workaround | |
not known / see Local fix | |
Comment | |
This APAR is a duplicate of IT13966 | |
Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 18.07.2016 09.12.2016 09.12.2016 |
Problem solved at the following versions (IBM BugInfos) | |
Problem solved according to the fixlist(s) of the following version(s) |