Am 03.10.2019 um 10:27 schrieb Thomas Plant:
Hello,

we have a client VM with MariaDB 10.4.8 which crashes always on the same
query (it's in the log). Can someone help me to debug the problem, or is
it already known problem? Server ist a CentOS 7 patched up to date and
MariaDB 10.4.8 from the MariaDB repositories.

Log contains the following:

191003  9:43:19 [ERROR] 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.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

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.

Server version: 10.4.8-MariaDB
key_buffer_size=134217728
read_buffer_size=131072
max_used_connections=1
max_threads=302
thread_count=7
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads =
795622 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x55d12dc0ed28
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...
stack_bottom = 0x7ff2fd21dcf0 thread_stack 0x49000
/usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x55d12b70483e]
/usr/sbin/mysqld(handle_fatal_signal+0x30f)[0x55d12b19ae0f]
sigaction.c:0(__restore_rt)[0x7ff3153325f0]
/usr/sbin/mysqld(handler_index_cond_check+0xbf)[0x55d12b1a56af]
/usr/sbin/mysqld(+0x59ee80)[0x55d12ae94e80]
/usr/sbin/mysqld(+0xb340cd)[0x55d12b42a0cd]
/usr/sbin/mysqld(+0xa52c87)[0x55d12b348c87]
/usr/sbin/mysqld(+0xa52edf)[0x55d12b348edf]
/usr/sbin/mysqld(_ZN7handler11ha_rnd_nextEPh+0x10f)[0x55d12b19f8ff]
/usr/sbin/mysqld(_Z13rr_sequentialP11READ_RECORD+0x1c)[0x55d12b2cde9c]
/usr/sbin/mysqld(_Z10sub_selectP4JOINP13st_join_tableb+0x1a9)[0x55d12afc7dd9]
/usr/sbin/mysqld(_ZN4JOIN10exec_innerEv+0xb9c)[0x55d12afea4cc]
/usr/sbin/mysqld(_ZN4JOIN4execEv+0x33)[0x55d12afea723]
/usr/sbin/mysqld(_Z12mysql_selectP3THDP10TABLE_LISTjR4ListI4ItemEPS4_jP8st_orderS9_S7_S9_yP13select_resultP18st_select_lex_unitP13st_select_lex+0x186)[0x55d12afe8a26]

/usr/sbin/mysqld(_Z13handle_selectP3THDP3LEXP13select_resultm+0x1d7)[0x55d12afe9597]
/usr/sbin/mysqld(+0x58dd2a)[0x55d12ae83d2a]
/usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x4591)[0x55d12af90641]
/usr/sbin/mysqld(_ZN18Prepared_statement7executeEP6Stringb+0x4b6)[0x55d12afa8d06]
/usr/sbin/mysqld(_ZN18Prepared_statement12execute_loopEP6StringbPhS2_+0x92)[0x55d12afa8ec2]
/usr/sbin/mysqld(+0x6b3827)[0x55d12afa9827]
/usr/sbin/mysqld(_Z19mysqld_stmt_executeP3THDPcj+0x27)[0x55d12afa98b7]
/usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcjbb+0x1625)[0x55d12af97d85]
/usr/sbin/mysqld(_Z10do_commandP3THD+0x11c)[0x55d12af99aac]
/usr/sbin/mysqld(_Z24do_handle_one_connectionP7CONNECT+0x1fa)[0x55d12b07718a]
/usr/sbin/mysqld(handle_one_connection+0x3d)[0x55d12b07726d]
pthread_create.c:0(start_thread)[0x7ff31532ae65]
/lib64/libc.so.6(clone+0x6d)[0x7ff3136cb88d]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x55d12dc24b38): select * from `users` where (`role` = ? or
`role` = ?) and exists (select * from `email_templates` inner join
`users_email` on `email_template
s`.`id` = `users_email`.`email_template_id` where `users`.`id` =
`users_email`.`user_id` and `email_template_id` = ?) and
`users`.`deleted_at` is null
Connection ID (thread ID): 9
Status: NOT_KILLED

Optimizer switch:
index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdow
n=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_
merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_increme
ntal=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=on,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition
_pushdown_for_derived=on,split_materialized=on,condition_pushdown_for_subquery=on,rowid_filter=on,condition_pushdown_from_having=on

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains
information that should help you find out what is causing the crash.
Writing a core file...
Working directory at /var/lib/mysql
Resource Limits:
Limit                     Soft Limit           Hard Limit           Units
Max cpu time              unlimited            unlimited            seconds
Max file size             unlimited            unlimited            bytes
Max data size             unlimited            unlimited            bytes
Max stack size            8388608              unlimited            bytes
Max core file size        0                    unlimited            bytes
Max resident set          unlimited            unlimited            bytes
Max processes             15028                15028               
processes
Max open files            16364                16364                files
Max locked memory         65536                65536                bytes
Max address space         unlimited            unlimited            bytes
Max file locks            unlimited            unlimited            locks
Max pending signals       15028                15028                signals
Max msgqueue size         819200               819200               bytes
Max nice priority         0                    0
Max realtime priority     0                    0
Max realtime timeout      unlimited            unlimited            us
Core pattern: core


Thanks for any hint.
Kind Regards,
Thomas

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Client did some tests and he discovered that the following query will crash reliably:


SELECT
*
FROM
`users`
WHERE
( `role` = 1 OR `role` = 10 )
AND EXISTS ( SELECT * FROM `email_templates` INNER JOIN `users_email` ON
`email_templates`.`id` = `users_email`.`email_template_id` WHERE
`users`.`id` = `users_email`.`user_id` AND `email_template_id` = 12 )
AND `users`.`deleted_at` IS NULL;


Strange thing is when he changes the
`email_template_id` = 12 to `email_template_id` = 11 (or any other value) the query works.

I checked with "mysqlcheck -ce dbname" and no error resulted.