MariaDB [(none)]> show processlist;

+----+------+-----------+------+---------+------+----------------------+--------------------------------------------------------------------+----------+

| Id | User | Host      | db   | Command | Time | State                | Info                                                               | Progress |

+----+------+-----------+------+---------+------+----------------------+--------------------------------------------------------------------+----------+

|  5 | root | localhost | NULL | Query   |   42 | After opening tables | RENAME TABLE ibis_staging.domain_access TO ibis_test.domain_access |    0.000 |

|  6 | root | localhost | NULL | Query   |    0 | init                 | show processlist                                                   |    0.000 |

+----+------+-----------+------+---------+------+----------------------+--------------------------------------------------------------------+----------+

2 rows in set (0.00 sec)

MariaDB [(none)]>

MariaDB [(none)]> select * from information_schema.metadata_lock_info;

+-----------+-------------------------+-----------------+----------------------+--------------+---------------+

| THREAD_ID | LOCK_MODE               | LOCK_DURATION   | LOCK_TYPE            | TABLE_SCHEMA | TABLE_NAME    |

+-----------+-------------------------+-----------------+----------------------+--------------+---------------+

|         5 | MDL_INTENTION_EXCLUSIVE | MDL_STATEMENT   | Global read lock     |              |               |

|         5 | MDL_INTENTION_EXCLUSIVE | MDL_TRANSACTION | Schema metadata lock | ibis_test    |               |

|         5 | MDL_SHARED_WRITE        | MDL_TRANSACTION | Table metadata lock  | mysql        | index_stats   |

|         5 | MDL_SHARED_WRITE        | MDL_TRANSACTION | Table metadata lock  | mysql        | table_stats   |

|         5 | MDL_EXCLUSIVE           | MDL_TRANSACTION | Table metadata lock  | ibis_staging | domain_access |

|         5 | MDL_INTENTION_EXCLUSIVE | MDL_TRANSACTION | Schema metadata lock | ibis_staging |               |

|         5 | MDL_EXCLUSIVE           | MDL_TRANSACTION | Table metadata lock  | ibis_test    | domain_access |

|         5 | MDL_SHARED_WRITE        | MDL_TRANSACTION | Table metadata lock  | mysql        | column_stats  |

+-----------+-------------------------+-----------------+----------------------+--------------+---------------+

8 rows in set (0.00 sec)

lsof -p 15772 | grep mysql/

mysqld  15772 mysql  mem    REG              202,1       10728       321 /usr/lib/mysql/plugin/query_response_time.so

mysqld  15772 mysql  mem    REG              202,1       10552     14555 /usr/lib/mysql/plugin/metadata_lock_info.so

mysqld  15772 mysql  mem    REG              202,1       10648     14778 /usr/lib/mysql/plugin/sql_errlog.so

mysqld  15772 mysql  mem    REG              202,1     1358656     14867 /usr/lib/mysql/plugin/ha_connect.so

mysqld  15772 mysql   15uW  REG             202,80    14680064    299539 /srv/mysqldata/mysql/innodb_index_stats.ibd

mysqld  15772 mysql   16uW  REG             202,80      245760    299537 /srv/mysqldata/mysql/innodb_table_stats.ibd

mysqld  15772 mysql   29w   REG              202,1     2167223    135538 /var/log/mysql/slow.log

mysqld  15772 mysql   30u   REG             202,80        1024       158 /srv/mysqldata/mysql/servers.MYI

mysqld  15772 mysql   31u   REG             202,80           0       159 /srv/mysqldata/mysql/servers.MYD

mysqld  15772 mysql   35u   REG             202,80        2048    299541 /srv/mysqldata/mysql/host.MYI

mysqld  15772 mysql   36u   REG             202,80           0    299542 /srv/mysqldata/mysql/host.MYD

mysqld  15772 mysql   37u   REG             202,80        4096    299526 /srv/mysqldata/mysql/user.MYI

mysqld  15772 mysql   38u   REG             202,80        1236    299557 /srv/mysqldata/mysql/user.MYD

mysqld  15772 mysql   39u   REG             202,80        9216       147 /srv/mysqldata/mysql/db.MYI

mysqld  15772 mysql   40u   REG             202,80        5688       156 /srv/mysqldata/mysql/db.MYD

mysqld  15772 mysql   41u   REG             202,80       10240    299522 /srv/mysqldata/mysql/proxies_priv.MYI

mysqld  15772 mysql   42u   REG             202,80        1269    299523 /srv/mysqldata/mysql/proxies_priv.MYD

mysqld  15772 mysql   43u   REG             202,80        4096       149 /srv/mysqldata/mysql/roles_mapping.MYI

mysqld  15772 mysql   44u   REG             202,80           0       150 /srv/mysqldata/mysql/roles_mapping.MYD

mysqld  15772 mysql   45u   REG             202,80        4096    299555 /srv/mysqldata/mysql/tables_priv.MYI

mysqld  15772 mysql   46u   REG             202,80           0    299556 /srv/mysqldata/mysql/tables_priv.MYD

mysqld  15772 mysql   47u   REG             202,80        4096       164 /srv/mysqldata/mysql/columns_priv.MYI

mysqld  15772 mysql   48u   REG             202,80           0       165 /srv/mysqldata/mysql/columns_priv.MYD

mysqld  15772 mysql   49u   REG             202,80        4096    299535 /srv/mysqldata/mysql/procs_priv.MYI

mysqld  15772 mysql   50u   REG             202,80           0    299540 /srv/mysqldata/mysql/procs_priv.MYD

mysqld  15772 mysql   52u   REG             202,80        2048    299536 /srv/mysqldata/mysql/event.MYI

mysqld  15772 mysql   53u   REG             202,80           0    299538 /srv/mysqldata/mysql/event.MYD

mysqld  15772 mysql   54uW  REG             202,80       98304    299553 /srv/mysqldata/mysql/gtid_slave_pos.ibd

mysqld  15772 mysql  205u   REG             202,80       51200    299544 /srv/mysqldata/mysql/table_stats.MYI

mysqld  15772 mysql  207u   REG             202,80       45444    299545 /srv/mysqldata/mysql/table_stats.MYD

mysqld  15772 mysql  208u   REG             202,80      289792    299547 /srv/mysqldata/mysql/column_stats.MYI

mysqld  15772 mysql  209u   REG             202,80     2003952    299548 /srv/mysqldata/mysql/column_stats.MYD

mysqld  15772 mysql  210u   REG             202,80      550912    299550 /srv/mysqldata/mysql/index_stats.MYI

mysqld  15772 mysql  211u   REG             202,80     1711376    299551 /srv/mysqldata/mysql/index_stats.MYD

MariaDB [test]> show processlist;

ERROR 2006 (HY000): MySQL server has gone away

No connection. Trying to reconnect...

Connection id:    8

Current database: test

+----+------+-----------+------+---------+------+----------------------+---------------------------+----------+

| Id | User | Host      | db   | Command | Time | State                | Info                      | Progress |

+----+------+-----------+------+---------+------+----------------------+---------------------------+----------+

|  4 | root | localhost | test | Killed  |  583 | After opening tables | rename table x to test1.x |    0.000 |

|  8 | root | localhost | test | Query   |    0 | init                 | show processlist          |    0.000 |

+----+------+-----------+------+---------+------+----------------------+---------------------------+----------+

151108 16:00:27 [Note] sql/mysqld: Normal shutdown

151108 16:00:27 [Note] Event Scheduler: Purging the queue. 0 events

151108 16:00:47 [Warning] sql/mysqld: Forcing close of thread 4  user: 'root'

151108 16:00:47 [ERROR] mysqld: Got an error writing communication packets

 (gdb) break sql_statistics.cc:3296

Breakpoint 1 at 0x6a5590: file /home/dan/software_projects/mariadb-server/sql/sql_statistics.cc, line 3296.

(gdb) c

Continuing.

[New Thread 0x7fef510f4700 (LWP 28730)]

[Switching to Thread 0x7fef510f4700 (LWP 28730)]

Breakpoint 1, rename_table_in_stat_tables (thd=0x7fef45e78008, db=0x7fef510f1f50, tab=0x7fef510f1f40, new_db=0x7fef510f1f50, new_tab=0x7fef510f1f30)

    at /home/dan/software_projects/mariadb-server/sql/sql_statistics.cc:3297

3297      stat_table= tables[COLUMN_STAT].table;

(gdb) n

3298      Column_stat column_stat(stat_table, db, tab);

(gdb) n

3299      column_stat.set_full_table_name();

(gdb) p column_stat

$1 = {<Stat_table> = {_vptr.Stat_table = 0xcba8f0 <vtable for Column_stat+16>, stat_file = 0x7fef304c4b20, stat_key_length = 582, record = {0x7fef3044d020 "\377\003db1", 

      0x7fef3044d978 "\377"}, stat_key_idx = 0, stat_table = 0x7fef30504608, stat_key_info = 0x7fef30468288, table = 0x316264, table_share = 0x0, db_name = 0x7fef510f1f50, 

    table_name = 0x7fef510f1f40}, db_name_field = 0x7fef30433080, table_name_field = 0x7fef30433150, column_name_field = 0x7fef30433220, table_field = 0x18e}

(gdb) n

3300      while (column_stat.find_next_stat_for_prefix(2))

(gdb) p column_stat

$2 = {<Stat_table> = {_vptr.Stat_table = 0xcba8f0 <vtable for Column_stat+16>, stat_file = 0x7fef304c4b20, stat_key_length = 582, record = {0x7fef3044d020 "\377\003db1", 

      0x7fef3044d978 "\377"}, stat_key_idx = 0, stat_table = 0x7fef30504608, stat_key_info = 0x7fef30468288, table = 0x316264, table_share = 0x0, db_name = 0x7fef510f1f50, 

    table_name = 0x7fef510f1f40}, db_name_field = 0x7fef30433080, table_name_field = 0x7fef30433150, column_name_field = 0x7fef30433220, table_field = 0x18e}

(gdb) s

Stat_table::find_next_stat_for_prefix (this=0x7fef510f0bc0, prefix_parts=2) at /home/dan/software_projects/mariadb-server/sql/sql_statistics.cc:487

487         uint prefix_key_length= 0;

(gdb) n

488         for (uint i= 0; i < prefix_parts; i++)

(gdb) n

489           prefix_key_length+= stat_key_info->key_part[i].store_length;

(gdb) n

488         for (uint i= 0; i < prefix_parts; i++)

(gdb) n

489           prefix_key_length+= stat_key_info->key_part[i].store_length;

(gdb) n

488         for (uint i= 0; i < prefix_parts; i++)

(gdb) n

490         key_copy(key, record[0], stat_key_info, prefix_key_length);

(gdb) p prefix_key_length

$3 = 388

(gdb) p record

$4 = {0x7fef3044d020 "\377\003db1", 0x7fef3044d978 "\377"}

(gdb) p record[0]

$5 = (uchar *) 0x7fef3044d020 "\377\003db1"

(gdb) p stat_key_info

$6 = (KEY *) 0x7fef30468288

(gdb) p *stat_key_info

$7 = {key_length = 582, flags = 41, user_defined_key_parts = 3, usable_key_parts = 3, ext_key_parts = 3, ext_key_flags = 41, ext_key_part_map = 0, block_size = 3072, name_length = 7, 

  algorithm = HA_KEY_ALG_UNDEF, is_statistics_from_stat_tables = false, {parser = 0x0, parser_name = 0x0}, key_part = 0x7fef30468330, name = 0x7fef30432d41 "PRIMARY", 

  cache_name = 0x7fef30467748 "mysql", rec_per_key = 0x7fef30432d50, read_stats = 0x0, collected_stats = 0x0, handler = {bdb_return_if_eq = 0}, table = 0x7fef30504608, comment = {str = 0x0, 

    length = 0}, option_list = 0x0, option_struct = 0x0}

(gdb) n

[New Thread 0x7fef510ab700 (LWP 28808)]

491         key_part_map prefix_map= (key_part_map) ((1 << prefix_parts) - 1);

(gdb) p *key

$8 = 3 '\003'

(gdb) p key

$9 = "\003\000db1", '\000' <repeats 189 times>, "\002\000t1", '\000' <repeats 194 times>...

(gdb) n

492         return !stat_file->ha_index_read_idx_map(record[0], stat_key_idx, key,

(gdb) n

493                                                  prefix_map, HA_READ_KEY_EXACT);

(gdb) n

494       }

(gdb) n

rename_table_in_stat_tables (thd=0x7fef45e78008, db=0x7fef510f1f50, tab=0x7fef510f1f40, new_db=0x7fef510f1f50, new_tab=0x7fef510f1f30)

    at /home/dan/software_projects/mariadb-server/sql/sql_statistics.cc:3302

3302        err= column_stat.update_table_name_key_parts(new_db, new_tab);

(gdb) p err

$10 = 0

(gdb) p column_stat

$11 = {<Stat_table> = {_vptr.Stat_table = 0xcba8f0 <vtable for Column_stat+16>, stat_file = 0x7fef304c4b20, stat_key_length = 582, record = {0x7fef3044d020 "\337\003db1",

      0x7fef3044d978 "\377"}, stat_key_idx = 0, stat_table = 0x7fef30504608, stat_key_info = 0x7fef30468288, table = 0x316264, table_share = 0x0, db_name = 0x7fef510f1f50,

    table_name = 0x7fef510f1f40}, db_name_field = 0x7fef30433080, table_name_field = 0x7fef30433150, column_name_field = 0x7fef30433220, table_field = 0x18e}

(gdb) n

3303        if (err & !rc)

(gdb) n

3305        column_stat.set_full_table_name();

(gdb) n

3300      while (column_stat.find_next_stat_for_prefix(2))

(gdb) p column_stat

$12 = {<Stat_table> = {_vptr.Stat_table = 0xcba8f0 <vtable for Column_stat+16>, stat_file = 0x7fef304c4b20, stat_key_length = 582, record = {0x7fef3044d020 "\337\003db1",

      0x7fef3044d978 "\337\003db1"}, stat_key_idx = 0, stat_table = 0x7fef30504608, stat_key_info = 0x7fef30468288, table = 0x316264, table_share = 0x0, db_name = 0x7fef510f1f50,

    table_name = 0x7fef510f1f40}, db_name_field = 0x7fef30433080, table_name_field = 0x7fef30433150, column_name_field = 0x7fef30433220, table_field = 0x18e}

(gdb) n

3302        err= column_stat.update_table_name_key_parts(new_db, new_tab);

(gdb) p column_stat

$13 = {<Stat_table> = {_vptr.Stat_table = 0xcba8f0 <vtable for Column_stat+16>, stat_file = 0x7fef304c4b20, stat_key_length = 582, record = {0x7fef3044d020 "\337\003db1",

      0x7fef3044d978 "\337\003db1"}, stat_key_idx = 0, stat_table = 0x7fef30504608, stat_key_info = 0x7fef30468288, table = 0x316264, table_share = 0x0, db_name = 0x7fef510f1f50,

    table_name = 0x7fef510f1f40}, db_name_field = 0x7fef30433080, table_name_field = 0x7fef30433150, column_name_field = 0x7fef30433220, table_field = 0x18e}

(gdb) wher

  #0  handler::ha_index_read_idx_map (this=0x7fff5802f0d8, buf=0x7fff580300d8

  "..." , index=0, key=0x7ffff42fe3c0 "\003", keypart_map=3, find_flag=HA_READ_KEY_EXACT) at /home/psergey/dev-git/10.1-dbg3/sql/handler.cc:2645

  #1  0x0000555555aeffee in Stat_table::find_next_stat_for_prefix (this=0x7ffff4300250, prefix_parts=2) at /home/psergey/dev-git/10.1-dbg3/sql/sql_statistics.cc:493

  #2  0x0000555555aee239 in rename_table_in_stat_tables (thd=0x55555aac6a80, db=0x7ffff4300450, tab=0x7ffff4300460, new_db=0x7ffff4300450, new_tab=0x7ffff4300470) at /home/psergey/dev-git/10.1-dbg3/sql/sql_statistics.cc:3300

  #3  0x0000555555a7346c in do_rename (thd=0x55555aac6a80, ren_table=0x7fff58007530, new_db=0x7fff580074f0 "db2", new_table_name=0x7fff580074f8 "t1", new_table_alias=0x7fff58007b18 "t1", skip_error=false) at /home/psergey/dev-git/10.1-dbg3/sql/sql_rename.cc:278

  #4  0x0000555555a73669 in rename_tables (thd=0x55555aac6a80, table_list=0x7fff58007530, skip_error=false) at /home/psergey/dev-git/10.1-dbg3/sql/sql_rename.cc:353

  #5  0x0000555555a73017 in mysql_rename_tables (thd=0x55555aac6a80, table_list=0x7fff58007530, silent=false) at /home/psergey/dev-git/10.1-dbg3/sql/sql_rename.cc:153

  #6  0x0000555555a4bb27 in mysql_execute_command (thd=0x55555aac6a80) at /home/psergey/dev-git/10.1-dbg3/sql/sql_parse.cc:3615

  #7  0x0000555555a57497 in mysql_parse (thd=0x55555aac6a80, rawbuf=0x7fff58007418 "rename table t1 to db2.t1", length=25, parser_state=0x7ffff4301100) at /home/psergey/dev-git/10.1-dbg3/sql/sql_parse.cc:7282

  #8  0x0000555555a4607e in dispatch_command (command=COM_QUERY, thd=0x55555aac6a80, packet=0x55555aacd0e1 "rename table t1 to db2.t1", packet_length=25) at /home/psergey/dev-git/10.1-dbg3/sql/sql_parse.cc:1488

  #9  0x0000555555a44dbf in do_command (thd=0x55555aac6a80) at /home/psergey/dev-git/10.1-dbg3/sql/sql_parse.cc:1110

  #10 0x0000555555b760f6 in do_handle_one_connection (thd_arg=0x55555aac6a80) at /home/psergey/dev-git/10.1-dbg3/sql/sql_connect.cc:1350

  #11 0x0000555555b75e47 in handle_one_connection (arg=0x55555aac6a80) at /home/psergey/dev-git/10.1-dbg3/sql/sql_connect.cc:1262

  #12 0x00007ffff691de9a in start_thread (arg=0x7ffff4302700) at pthread_create.c:308

  #13 0x00007ffff604e3fd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112

(gdb) p index_rows_read[index]

  $132 = 453061

(gdb) p this

  $133 = (handler * const) 0x7fff5802f0d8

(gdb) p table->alias.Ptr

  $134 = 0x7fff58028820 "column_stats"

(gdb) p index

  $135 = 0

MariaDB [test]> rename table x to y;

Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> rename table y to test.z;

Query OK, 0 rows affected (0.01 sec)

MariaDB [test]> rename table z to t2.y;

Query OK, 0 rows affected (0.00 sec)

{nofomrat}

Does rename_table_in_stat_tables work the same way as the sql 'update mysql.column_stats set db_name='destdb',table_name='desttable' where db_name='source_db' and table_name='source_table';

Interesting when mysql.column_stats is changed to innodb for a case where it lock waited:

MariaDB [(none)]> create database t2;

Query OK, 1 row affected (0.00 sec)

MariaDB [(none)]> use test;

Database changed

MariaDB [test]> create table t1 (x int, y varchar(30) default 'vodo');

Query OK, 0 rows affected (0.00 sec)

MariaDB [test]> insert into t1 values (2,'so'), (6, 'check'), (9, 'rocket');

Query OK, 3 rows affected (0.00 sec)

Records: 3  Duplicates: 0  Warnings: 0

MariaDB [test]> analyze table t1 persistent for all;

+---------+---------+----------+-----------------------------------------+

| Table   | Op      | Msg_type | Msg_text                                |

+---------+---------+----------+-----------------------------------------+

| test.t1 | analyze | status   | Engine-independent statistics collected |

| test.t1 | analyze | status   | OK                                      |

+---------+---------+----------+-----------------------------------------+

2 rows in set (0.00 sec)

MariaDB [test]> select * from mysql.column_stats;

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

| db_name | table_name | column_name | min_value | max_value | nulls_ratio | avg_length | avg_frequency | hist_size | hist_type | histogram |

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

| test    | t1         | x           | 2         | 9         |      0.0000 |     4.0000 |        1.0000 |         0 | NULL      | NULL      |

| test    | t1         | y           | check     | so        |      0.0000 |     4.3333 |        1.0000 |         0 | NULL      | NULL      |

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

2 rows in set (0.00 sec)

MariaDB [test]> alter table t1 add z varchar(30) default 'china', drop x, rename t2.t2;

Query OK, 0 rows affected (0.01 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> select * from mysql.column_stats;

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

| db_name | table_name | column_name | min_value | max_value | nulls_ratio | avg_length | avg_frequency | hist_size | hist_type | histogram |

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

| t2      | t2         | y           | check     | so        |      0.0000 |     4.3333 |        1.0000 |         0 | NULL      | NULL      |

+---------+------------+-------------+-----------+-----------+-------------+------------+---------------+-----------+-----------+-----------+

1 row in set (0.00 sec)