【MYSQL】state状态converting HEAP to MyISAM

背景：机房迁移，原报表系统在新的db上出报表非常慢

1.查看连接状态

1. mysql> show full processlist;
   
2. +--------+-----------------+---------------------+----------+---------+---------+-----------------------------------------------------------------------------+-----------------------+
   
3. | Id | User | Host | db | Command | Time | State | Info |
   
4. +--------+-----------------+---------------------+----------+---------+---------+-----------------------------------------------------------------------------+-----------------------+
   
5. | 1 | event_scheduler | localhost | NULL | Daemon | 2247681 | Waiting on empty queue | NULL |
   
6. | 121456 | system user | | NULL | Connect | 784383 | Waiting for master to send event | NULL |
   
7. | 121457 | system user | | NULL | Connect | 1 | Slave has read all relay log; waiting for the slave I/O thread to update it | NULL |
   
8. | 121468 | ecejadmin | 192.168.2.104:42497 | ecejdbv3 | converting HEAP to MyISAM | 1 | | 复杂sql                 |
   
9. | 121469 | ecejadmin | 192.168.2.10:54423 | ecejdbv3 | converting HEAP to MyISAM | 2 | | 复杂sql |
   
10. | 121470 | ecejadmin | 192.168.2.12:9386 | ecejdbv3 | converting HEAP to MyISAM | 1 | | 复杂sql |
    
11. | 121471 | ecejadmin | 192.168.2.104:63937 | ecejdbv3 | converting HEAP to MyISAM | 2 | | 复杂sql

报表sql状态如上

2.处理过程

1. 1.在终端里set profiling=1;
   
2. 2.输入要调整的SQL语句，比如复杂sql;
   
3. 3.输入show profiles;看看刚才那条语句的ID 用于后面分析
   
4. 4.show profile for query 2;
   
5. 5.show profile block io,cpu for query 2;
   
6. 6.show profile cpu,block io,memory,swaps,context switches,source for query 5;
   
7. 7.通过上面的一些查询 大体可以看出这条SQL语句执行的时候哪些地方占用的时间太大了。这次测试看到的是Copying to tmp table on disk和converting HEAP to MyISAM占有的时间太多。网上查了一下发现可以修改一下tmp_table_size和max_heap_table_size两个参数来调整，使得大数据量的查询时不用将结果集拷贝到物理磁盘。这样时间就争取过来了

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转载于:http://blog.itpub.net/29096438/viewspace-2144585/