如果对mysql表，进行大范围删除后，最好做一个表优化，这样会快一些。以前写过一篇类似的，针对myisam存储引擎的。请参考：实例说明optimize table在优化mysql时很重要
1，删除数据，并尝试优化
mysql> delete FROM `test` WHERE d_id>397136;
Query OK, 306356 rows affected (19.48 sec)
mysql> optimize table test;
+------------+----------+----------+-------------------------------------------------------------------+
| Table | Op | Msg_type | Msg_text |
+------------+----------+----------+-------------------------------------------------------------------+
| test1.test | optimize | note | Table does not support optimize, doing recreate + analyze instead |
| test1.test | optimize | status | OK |
+------------+----------+----------+-------------------------------------------------------------------+
2 rows in set (0.35 sec)
执行optimize的时候，非常慢，可能会卡死。msg_text信息的意思是innodb引擎，不支持optimize。在官网找了一下，发现以下内空
Table does not support optimize, doing recreate + analyze instead.
It is because the table that you are using is InnoDB.
You can optimize the InnoDB tables by using this.
ALTER TABLE table.name ENGINE='InnoDB';
一般情况下，由myisam转成innodb，会用alter table table.name engine='innodb'进行转换，优化也可以用这个
2，alter优化数据
mysql> alter table test engine='innodb';
Query OK, 384781 rows affected (19.88 sec)
Records: 384781 Duplicates: 0 Warnings: 0
alter如果很慢，优化一下my.cnf，[mysqld]加上以下内容，并重新加载。
innodb_buffer_pool_size=1G
innodb_file_io_threads=4
innodb_file_io_threads常规配置，小于等CPU核数。innodb_buffer_pool_size小于等于物理内存的1/2，原则上够用就好。
3，优化后的对比
mysql> use information_schema
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB,
-> concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
-> from tables where
-> table_schema='test1'
-> and table_name = 'test';
+----------------+-----------------+
| data_length_MB | index_length_MB |
+----------------+-----------------+
| 20.55MB | 27.55MB | //优化前
+----------------+-----------------+
1 row in set (0.01 sec)
mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB,
-> concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
-> from tables where
-> table_schema='test1'
-> and table_name = 'test';
+----------------+-----------------+
| data_length_MB | index_length_MB |
+----------------+-----------------+
| 20.55MB | 16.55MB | //优化后
+----------------+-----------------+
1 row in set (0.00 sec)
data_length_MB，第一列是数据；index_length_MB，第二列是索引