What problem does this PR solve?

• refactor slow log format to compatible with mysql slow log.
• Add INFORMATION_SCHEMA.SLOW_QUERY table, the table content is from parse slow log file.
• Add tidb_slow_query_file seesion variable to control which slow log file to be parsed.

What is changed and how it works?

• New slow log format is like below, this will be friendly to some utils like pt-query-digest.

  # Time: 2019-02-12-19:33:56.571953 +0800
  # Txn_start_ts: 406315658548871171
  # User: [email protected]
  # Conn_ID: 6
  # Query_time: 4.895492
  # Process_time: 0.161 Request_count: 1 Total_keys: 100001 Processed_keys: 100000
  # DB: test
  # Is_internal: false
  select * from t_slim;
  

  • other information like statement digest, plan digest maybe add later.
  • If you need more information in slow log, please leave you comment.

• Query INFORMATION_SCHEMA.SLOW_QUERY table.

  mysql> use INFORMATION_SCHEMA;
  Database changed
  mysql> set @@tidb_slow_query_file="tidb_slow.log";
  Query OK, 0 rows affected (0.00 sec)
  mysql> select * from `SLOW_QUERY`;
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  | Time                       | Txn_start_ts       | User           | Conn_ID | Query_time | Process_time | Wait_time | Backoff_time | Request_count | Total_keys | Processed_keys | DB   | Is_internal | Query                                            |
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  | 2019-02-12 19:31:06.954777 | 406315605634056194 | root@127.0.0.1 |       1 |  37.142122 |         NULL |      NULL |         NULL |          NULL |       NULL |           NULL | test |           0 | create table t1(y year NOT NULL DEFAULT '2155'); |
  | 2019-02-12 19:33:56.571953 | 406315658548871171 | root@127.0.0.1 |       6 |   4.895492 |        0.161 |      NULL |         NULL |             1 |     100001 |         100000 | test |           0 | select * from t_slim;                            |
  | 2019-02-12 19:34:33.257245 |                  0 | NULL           |    NULL |    0.51371 |         NULL |      NULL |         NULL |          NULL |       NULL |           NULL | NULL |           1 | analyze table `test`.`t_slim`;                   |
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  3 rows in set (0.00 sec)
  
  mysql> select * from `SLOW_QUERY` where `Is_internal`=false order by `Query_time` desc;
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  | Time                       | Txn_start_ts       | User           | Conn_ID | Query_time | Process_time | Wait_time | Backoff_time | Request_count | Total_keys | Processed_keys | DB   | Is_internal | Query                                            |
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  | 2019-02-12 19:31:06.954777 | 406315605634056194 | root@127.0.0.1 |       1 |  37.142122 |         NULL |      NULL |         NULL |          NULL |       NULL |           NULL | test |           0 | create table t1(y year NOT NULL DEFAULT '2155'); |
  | 2019-02-12 19:33:56.571953 | 406315658548871171 | root@127.0.0.1 |       6 |   4.895492 |        0.161 |      NULL |         NULL |             1 |     100001 |         100000 | test |           0 | select * from t_slim;                            |
  +----------------------------+--------------------+----------------+---------+------------+--------------+-----------+--------------+---------------+------------+----------------+------+-------------+--------------------------------------------------+
  2 rows in set (0.00 sec)

Check List

Tests

• Unit test
• Integration test

Code changes

• Has exported function/method change

Side effects

Related changes

• Need to update the documentation