The problem was found during RQG testing on MariaDB 10.4 30641f9df77be99d93524e39cdc2b2d783e6d3e1 2018-12-18

compiled with debug.

There was no replay of the assert on actual 10.3.

ts_4.test

--------------

--source include/have_innodb.inc

 CREATE TABLE IF NOT EXISTS t1 (col1 INT, col2 INT, col_int INTEGER, col_varchar VARCHAR(500), col_text TEXT, col_int_g INTEGER GENERATED ALWAYS AS (col_int) PERSISTENT) ENGINE = InnoDB ROW_FORMAT = Redundant  ;

 ALTER TABLE t1 ADD COLUMN IF NOT EXISTS col2_copy INT FIRST;

 ALTER TABLE t1 ADD COLUMN col1_copy INT FIRST;

 ALTER TABLE t1 ADD COLUMN IF NOT EXISTS col_int_copy INTEGER;

 ALTER TABLE t1 MODIFY COLUMN col_text TEXT NOT NULL;

 ALTER TABLE t1 CHANGE COLUMN IF EXISTS col_text col_text TEXT  ;

ALTER TABLE t1 MODIFY COLUMN col_int INTEGER AFTER col1;

--enable_abort_on_error

SHOW PROCESSLIST;

Version: '10.4.1-MariaDB-debug-log'  socket: ..

mysqld: storage/innobase/handler/handler0alter.cc:393: void dict_table_t::prepare_instant(const dict_table_t&, const ulint*, unsigned int&): Assertion `(((core_null) + 7) / 8) == oindex.n_core_null_bytes' failed.

181220 18:45:46 [ERROR] mysqld got signal 6 ;

...

Query (0x7f5118014190): ALTER TABLE t1 MODIFY COLUMN col_int INTEGER AFTER col1

Connection ID (thread ID): 9

Status: NOT_KILLED

...

Thread 1 (Thread 0x7f5169ce5700 (LWP 23599)):

#0  __pthread_kill (threadid=<optimized out>, signo=6) at ../sysdeps/unix/sysv/linux/pthread_kill.c:57

#1  0x000055d41183db94 in my_write_core (sig=6) at mysys/stacktrace.c:481

#2  0x000055d411083ca3 in handle_fatal_signal (sig=6) at sql/signal_handler.cc:305

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51

#5  0x00007f51709c0f5d in __GI_abort () at abort.c:90

#6  0x00007f51709b6f17 in __assert_fail_base (fmt=<optimized out>, assertion=assertion@entry=0x55d411b2dd70 "(((core_null) + 7) / 8) == oindex.n_core_null_bytes", file=file@entry=0x55d411b2d980 "storage/innobase/handler/handler0alter.cc", line=line@entry=393, function=function@entry=0x55d411b35ea0 <dict_table_t::prepare_instant(dict_table_t const&, unsigned long const*, unsigned int&)::__PRETTY_FUNCTION__> "void dict_table_t::prepare_instant(const dict_table_t&, const ulint*, unsigned int&)") at assert.c:92

#7  0x00007f51709b6fc2 in __GI___assert_fail (assertion=0x55d411b2dd70 "(((core_null) + 7) / 8) == oindex.n_core_null_bytes", file=0x55d411b2d980 "storage/innobase/handler/handler0alter.cc", line=393, function=0x55d411b35ea0 <dict_table_t::prepare_instant(dict_table_t const&, unsigned long const*, unsigned int&)::__PRETTY_FUNCTION__> "void dict_table_t::prepare_instant(const dict_table_t&, const ulint*, unsigned int&)") at assert.c:101

#8  0x000055d4112f1fc8 in dict_table_t::prepare_instant (this=0x7f51181a2958, old=..., col_map=0x7f511818cc90, first_alter_pos=@0x7f51180166e8: 4) at storage/innobase/handler/handler0alter.cc:393

#9  0x000055d4112f6291 in ha_innobase_inplace_ctx::prepare_instant (this=0x7f5118016578) at storage/innobase/handler/handler0alter.cc:1020

#10 0x000055d4112e15cb in prepare_inplace_alter_table_dict (ha_alter_info=0x7f5169ce1bb0, altered_table=0x7f51181832d8, old_table=0x7f5118178f58, table_name=0x7f511818a2a5 "t1", flags=0, flags2=80, fts_doc_id_col=18446744073709551615, add_fts_doc_id=false, add_fts_doc_id_idx=false) at storage/innobase/handler/handler0alter.cc:6420

#11 0x000055d4112e6490 in ha_innobase::prepare_inplace_alter_table (this=0x7f51181851c0, altered_table=0x7f51181832d8, ha_alter_info=0x7f5169ce1bb0) at storage/innobase/handler/handler0alter.cc:7966

#12 0x000055d41108ff1f in handler::ha_prepare_inplace_alter_table (this=0x7f51181851c0, altered_table=0x7f51181832d8, ha_alter_info=0x7f5169ce1bb0) at sql/handler.cc:4472

#13 0x000055d410e51037 in mysql_inplace_alter_table (thd=0x7f5118000ce8, table_list=0x7f51180142a8, table=0x7f5118178f58, altered_table=0x7f51181832d8, ha_alter_info=0x7f5169ce1bb0, inplace_supported=HA_ALTER_INPLACE_INSTANT, target_mdl_request=0x7f5169ce1ce0, alter_ctx=0x7f5169ce28d0) at sql/sql_table.cc:7505

#14 0x000055d410e57286 in mysql_alter_table (thd=0x7f5118000ce8, new_db=0x7f51180053b0, new_name=0x7f5118005780, create_info=0x7f5169ce34c0, table_list=0x7f51180142a8, alter_info=0x7f5169ce3400, order_num=0, order=0x0, ignore=false) at sql/sql_table.cc:9688

#15 0x000055d410ee126e in Sql_cmd_alter_table::execute (this=0x7f5118014a08, thd=0x7f5118000ce8) at sql/sql_alter.cc:491

#16 0x000055d410d7f8d0 in mysql_execute_command (thd=0x7f5118000ce8) at sql/sql_parse.cc:6302

#17 0x000055d410d84a8c in mysql_parse (thd=0x7f5118000ce8, rawbuf=0x7f5118014190 "ALTER TABLE t1 MODIFY COLUMN col_int INTEGER AFTER col1", length=55, parser_state=0x7f5169ce45f0, is_com_multi=false, is_next_command=false) at sql/sql_parse.cc:8104

#18 0x000055d410d719ba in dispatch_command (command=COM_QUERY, thd=0x7f5118000ce8, packet=0x7f511800acd9 "ALTER TABLE t1 MODIFY COLUMN col_int INTEGER AFTER col1", packet_length=55, is_com_multi=false, is_next_command=false) at sql/sql_parse.cc:1850

#19 0x000055d410d703cf in do_command (thd=0x7f5118000ce8) at sql/sql_parse.cc:1395

#20 0x000055d410edb29e in do_handle_one_connection (connect=0x55d4140773b8) at sql/sql_connect.cc:1402

#21 0x000055d410edb015 in handle_one_connection (arg=0x55d4140773b8) at sql/sql_connect.cc:1308

#22 0x000055d4117d5d63 in pfs_spawn_thread (arg=0x55d4140ddd08) at storage/perfschema/pfs.cc:1862

#23 0x00007f51716627fc in start_thread (arg=0x7f5169ce5700) at pthread_create.c:465

#24 0x00007f5170a9cb5f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95