Version: '5.1.17-beta-debug' socket: '/tmp/mysql.sock' port: 3306 yes 070304 8:21:04 [Note] SCHEDULER: Loaded 0 events mysqld got signal 11; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=8388600 read_buffer_size=131072 max_used_connections=2 max_threads=151 threads_connected=2 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 337599 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. thd: 0x8ef1cb8 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... Cannot determine thread, fp=0x428cba0c, backtrace may not be correct. Stack range sanity check OK, backtrace follows: 0x821fb55 handle_segfault + 429 0x82100d7 _ZN11Query_arena10free_itemsEv + 85 0x820cfca _ZN3THD19cleanup_after_queryEv + 174 0x82359a8 _Z11mysql_parseP3THDPcj + 540 0x822ae51 _Z16dispatch_command19enum_server_commandP3THDPcj + 1985 0x822a685 _Z10do_commandP3THD + 621 0x8229283 handle_one_connection + 259 0x4004daa7 _end + 930973047 0x4017ec2e _end + 932222718 New value of fp=(nil) failed sanity check, terminating stack trace! Please read http://dev.mysql.com/doc/mysql/en/using-stack-trace.html and follow instructions on how to resolve the stack trace. Resolved stack trace is much more helpful in diagnosing the problem, so please do resolve it Trying to get some variables. Some pointers may be invalid and cause the dump to abort... thd->query at 0x8efb300 = select 1 from ( select sum(`a`) from `t1` group by `a` with rollup) as `a` thd->thread_id=5 The manual page at http://www.mysql.com/doc/en/Crashing.html contains information that should help you find out what is causing the crash.