背景：機房遷移，原報表系統在新的db上出報表非常慢

1.檢視連線狀態

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

報表sql狀態如上

2.處理過程

1.在終端裡set profiling=1;
2.輸入要調整的SQL語句，比如複雜sql;
3.輸入show profiles;看看剛才那條語句的ID 用於後面分析
4.show profile for query 2;
5.show profile block io,cpu for query 2;
6.show profile cpu,block io,memory,swaps,context switches,source for query 5;
7.透過上面的一些查詢大體可以看出這條SQL語句執行的時候哪些地方佔用的時間太大了。這次測試看到的是Copying to tmp table on disk和converting HEAP to MyISAM佔有的時間太多。網上查了一下發現可以修改一下tmp_table_size和max_heap_table_size兩個引數來調整，使得大資料量的查詢時不用將結果集複製到物理磁碟。這樣時間就爭取過來了

【MYSQL】state狀態converting HEAP to MyISAM

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