mysql优化: waiting for.. Copying to tmp table

mysql优化: waiting for.. Copying to tmp table

因为临时的结果集大于mysql中tmp_table_size设置的大小，默认是16M,mysql会将数据转存到磁盘

mysql> show variables like '%tmp%';
+-------------------+---------------+
| Variable_name     | Value         |
+-------------------+---------------+
| max_tmp_tables    | 32            |
| slave_load_tmpdir | /pd/mysql_tmp |
| tmp_table_size    | 16777216      |
| tmpdir            | /pd/mysql_tmp |
+-------------------+---------------+
4 rows in set

解决方案

调整tmp_table_size大小