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第 16 章 MySQL 大数据操作注意事项

http://netkiller.github.io/journal/mysql.parallel.html

目录

16.1. 关于 delete
16.2. 关于 update
16.3. 关于创建索引
16.4. 关于 OPTIMIZE
16.5. 关于切换引擎
16.6. 确保SELECT不被受阻

16.1. 关于 delete

delete from mytable 必死无疑,你需要分批删除,尽量缩小每个批次删除的记录数,delete 是可以并行执行的,你可以同时运行多个删除操作

		
mysql> show processlist;
+--------+-----------------+---------------------+-----------+---------+-------+-----------------------------+--------------------------------------------------------+
| Id     | User            | Host                | db        | Command | Time  | State                       | Info                                                   |
+--------+-----------------+---------------------+-----------+---------+-------+-----------------------------+--------------------------------------------------------+
|      1 | event_scheduler | localhost           | NULL      | Daemon  |    52 | Waiting for next activation | NULL                                                   |
| 115986 | dba             | localhost           | example   | Query   |     0 | NULL                        | show processlist                                       |
| 117446 | dba             | localhost           | example   | Query   |    20 | updating                    | delete from mytable where OPEN_TIME like '2011.11.28%' |
| 117525 | dba             | localhost           | example   | Query   |     2 | updating                    | delete from mytable where OPEN_TIME like '2011.12.02%' |
| 117526 | dba             | localhost           | example   | Query   |    49 | updating                    | delete from mytable where OPEN_TIME like '2011.12.12%' |
| 117527 | dba             | localhost           | example   | Query   |     6 | updating                    | delete from mytable where OPEN_TIME like '2011.12.21%' |
| 117528 | dba             | localhost           | example   | Query   |    64 | updating                    | delete from mytable where OPEN_TIME like '2011.12.30%' |
| 117546 | dba             | localhost           | example   | Query   |    33 | updating                    | delete from mytable where OPEN_TIME like '2011.11.10%' |
+--------+-----------------+---------------------+-----------+---------+-------+-----------------------------+--------------------------------------------------------+
23 rows in set (0.00 sec)