MariaDB [test]> CREATE TABLE ct (a INT NOT NULL PRIMARY KEY, b INT NOT NULL) ENGINE=CONNECT TABLE_TYPE=csv FILE_NAME='ct.csv';

Query OK, 0 rows affected, 1 warning (0.13 sec)

Warning (Code 1105): Open(rb) error 2 on /usr/local/mariadb-10.0.8-linux-x86_64/data/./test/ct.csv: No such file or directory

MariaDB [test]> ALTER TABLE ct ADD UNIQUE INDEX uni_a_b (a,b);

ERROR 2013 (HY000): Lost connection to MySQL server during query

ERROR 2006 (HY000): MySQL server has gone away

No connection. Trying to reconnect...

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (111 "Connection refused")

ERROR: Can't connect to the server

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (111 "Connection refused")

140319  1:48:31 [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 http://kb.askmonty.org/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: 10.0.8-MariaDB-log

key_buffer_size=134217728

read_buffer_size=131072

max_used_connections=1

max_threads=501

thread_count=2

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 1224384 K  bytes of memory

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

Thread pointer: 0x0x7f6b17be7008

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 = 0x7f6b32c4dd28 thread_stack 0x48000

/usr/local/mysql/bin/mysqld(my_print_stacktrace+0x2e)[0xb9020e]

/usr/local/mysql/bin/mysqld(handle_fatal_signal+0x44c)[0x70ceac]

/lib/x86_64-linux-gnu/libpthread.so.0(+0xf030)[0x7f6b3421e030]

/lib/x86_64-linux-gnu/libc.so.6(rewind+0x1)[0x7f6b33122121]

/usr/local/mysql/lib/plugin/ha_connect.so(_ZN6DOSFAM6RewindEv+0x18)[0x7f6b07ad11a8]

/usr/local/mysql/lib/plugin/ha_connect.so(_ZN6TDBDOS6OpenDBEP7_global+0x165)[0x7f6b07adf3a5]

/usr/local/mysql/lib/plugin/ha_connect.so(_ZN6TDBCSV6OpenDBEP7_global+0x24a)[0x7f6b07ae3cba]

/usr/local/mysql/lib/plugin/ha_connect.so(_ZN6TDBDOS9MakeIndexEP7_globalP8INDEXDEFb+0x1b5)[0x7f6b07ade8c5]

/usr/local/mysql/lib/plugin/ha_connect.so(_ZN10ha_connect13external_lockEP3THDi+0x4b4)[0x7f6b07ab9b54]

/usr/local/mysql/bin/mysqld(_ZN7handler16ha_external_lockEP3THDi+0x72)[0x70e152]

/usr/local/mysql/bin/mysqld(_Z19mysql_unlock_tablesP3THDP13st_mysql_lockb+0x5c)[0x7e230c]

/usr/local/mysql/bin/mysqld(_Z17mysql_lock_removeP3THDP13st_mysql_lockP5TABLE+0x91)[0x7e24d1]

/usr/local/mysql/bin/mysqld(_Z25close_all_tables_for_nameP3THDP11TABLE_SHARE17ha_extra_functionP5TABLE+0xd4)[0x54f434]

/usr/local/mysql/bin/mysqld[0x613bf0]

/usr/local/mysql/bin/mysqld(_Z17mysql_alter_tableP3THDPcS1_P14HA_CREATE_INFOP10TABLE_LISTP10Alter_infojP8st_orderb+0x35dc)[0x618f0c]

/usr/local/mysql/bin/mysqld(_ZN19Sql_cmd_alter_table7executeEP3THD+0x508)[0x663ca8]

/usr/local/mysql/bin/mysqld(_Z21mysql_execute_commandP3THD+0x7e2)[0x590392]

/usr/local/mysql/bin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x25a)[0x59790a]

/usr/local/mysql/bin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1827)[0x5996a7]

/usr/local/mysql/bin/mysqld(_Z10do_commandP3THD+0xe5)[0x599da5]

/usr/local/mysql/bin/mysqld(_Z26threadpool_process_requestP3THD+0xf8)[0x6a95e8]

/usr/local/mysql/bin/mysqld[0x6e11f8]

/usr/local/mysql/bin/mysqld[0xa30e7b]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x6b50)[0x7f6b34215b50]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f6b331920ed]

Trying to get some variables.

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

Query (0x7f6b314cb020): is an invalid pointer

Connection ID (thread ID): 4

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=off,exists_to_in=off

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.