Assertion failure when reporting duplicate key error in online table rebuild

            HACK HACK HACK

            Prepare the list of keys for an error message. 

            It must match what the engine does internally in ::add_index().

            Here we emulate what innobase_create_key_def() does.

            Luckily, in 10.0 this will go away.

170514 2:50:40 [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: 10.1.19-MariaDB

key_buffer_size=16777216

read_buffer_size=262144

max_used_connections=525

max_threads=1002

thread_count=246

It is possible that mysqld could use up to

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 806479 K bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0x7f7d954eb008

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 = 0x7eef5265b208 thread_stack 0x48400

(my_addr_resolve failure: fork)

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(my_print_stacktrace+0x2e) [0xc0e2fe]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(handle_fatal_signal+0x4ba) [0x76836a]

/lib64/libpthread.so.0() [0x3fe2a0f7e0]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(key_unpack(String*, TABLE*, st_key*)+0x95) [0x831c35]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(print_keydup_error(TABLE*, st_key*, char const*, unsigned long)+0x76) [0x76e136]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld() [0x91c3e3]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld() [0x63ce0b]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(mysql_alter_table(THD*, char*, char*, HA_CREATE_INFO*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool)+0x3c42) [0x644812]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(mysql_recreate_table(THD*, TABLE_LIST*, bool)+0x196) [0x644a26]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld() [0x69ba5e]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld() [0x69d4da]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(Sql_cmd_optimize_table::execute(THD*)+0xe6) [0x69e5d6]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(mysql_execute_command(THD*)+0x13db) [0x5b38bb]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(mysql_parse(THD*, char*, unsigned int, Parser_state*)+0x354) [0x5bbe54]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld() [0x5bbee8]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(dispatch_command(enum_server_command, THD*, char*, unsigned int)+0x14e5) [0x5bdfc5]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(do_command(THD*)+0x2a7) [0x5bf297]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(do_handle_one_connection(THD*)+0x183) [0x68e853]

/apps/mariadb/instances/sysmdbblpfrm/bin/mysqld(handle_one_connection+0x42) [0x68ea72]

/lib64/libpthread.so.0() [0x3fe2a07aa1]

/lib64/libc.so.6(clone+0x6d) [0x3fe22e8aad]

Trying to get some variables.

Some pointers may be invalid and cause the dump to abort.

Query (0x7f7d80b92020): OPTIMIZE TABLE some_db.some_table

Connection ID (thread ID): 10354269

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_pushdown=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_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=off