Запрос на * from information_schema.tables очень медленный. Innodb_stats_on_metadata выключен, и выберите table_name из таблиц быстро, просто выбрав несколько полей очень медленно (12 минут!)Выбирайте из таблицы information_schema очень медленно
mysql> select * from tables limit 1;
+---------------+--------------------+----------------+-------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------------+
| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME | TABLE_TYPE | ENGINE | VERSION | ROW_FORMAT | TABLE_ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | AUTO_INCREMENT | CREATE_TIME | UPDATE_TIME | CHECK_TIME | TABLE_COLLATION | CHECKSUM | CREATE_OPTIONS | TABLE_COMMENT |
+---------------+--------------------+----------------+-------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------------+
| def | information_schema | CHARACTER_SETS | SYSTEM VIEW | MEMORY | 10 | Fixed | NULL | 384 | 0 | 32869632 | 0 | 0 | NULL | 2016-12-19 23:55:46 | NULL | NULL | utf8_general_ci | NULL | max_rows=87381 | |
+---------------+--------------------+----------------+-------------+--------+---------+------------+------------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------------+
1 row in set (**12 min 27.02 sec**)
Дополнительная информация:
mysql> select count(*) from tables;
+----------+
| count(*) |
+----------+
| 194196 |
+----------+
1 row in set (0.57 sec)
mysql> show global variables like '%innodb%metada%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| innodb_stats_on_metadata | OFF |
+--------------------------+-------+
1 row in set (0.00 sec)
194196 столы, действительно? – Sebas