减少不必要的group by字段 - 数据库编程

ble | 0.000006 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000331 | 0.000000 | 0.000000 | 0 | 0 |
| logging slow query | 0.000006 | 0.000000 | 0.000000 | 0 | 0 |
| logging slow query | 0.000047 | 0.000000 | 0.000000 | 0 | 8 |
| cleaning up | 0.000005 | 0.000000 | 0.000000 | 0 | 0 |
+----------------------+-----------+----------+------------+--------------+---------------+

去掉多余字段后的profiling
+--------------------------------+----------+----------+------------+--------------+---------------+
| Status | Duration | CPU_user | CPU_system | Block_ops_in | Block_ops_out |
+--------------------------------+----------+----------+------------+--------------+---------------+
| starting | 0.000027 | 0.000000 | 0.000000 | 0 | 0 |
| Waiting for query cache lock | 0.000008 | 0.000000 | 0.000000 | 0 | 0 |
| checking query cache for query | 0.000082 | 0.000000 | 0.000000 | 0 | 0 |
| checking permissions | 0.000011 | 0.000000 | 0.000000 | 0 | 0 |
| Opening tables | 0.000020 | 0.000000 | 0.000000 | 0 | 0 |
| System lock | 0.000014 | 0.000000 | 0.000000 | 0 | 0 |
| Waiting for query cache lock | 0.000038 | 0.000000 | 0.000000 | 0 | 0 |
| init | 0.000040 | 0.000000 | 0.000000 | 0 | 0 |
| optimizing | 0.000019 | 0.000000 | 0.000000 | 0 | 0 |
| statistics | 0.000061 | 0.000000 | 0.000000 | 0 | 0 |
| preparing | 0.000051 | 0.000000 | 0.000000 | 0 | 0 |
| Creating tmp table | 0.000042 | 0.000000 | 0.000000 | 0 | 0 |

| Sorting for group | 5.275880 | 2.539614 | 6.813964 | 120 | 287368 |
| executing | 0.000011 | 0.000000 | 0.000000 | 0 | 0 |
| Copying to tmp table | 0.492344 | 0.478927 | 0.021997 | 24 | 264 |
| Sorting result | 0.018007 | 0.016997 | 0.001000 | 0 | 0 |
| Sending data | 0.000039 | 0.000000 | 0.000000 | 0 | 0 |
| end | 0.000005 | 0.000000 | 0.000000 | 0 | 0 |
| removing tmp table | 0.001028 | 0.000000 | 0.000999 | 0 | 0 |
| end | 0.000007 | 0.000000 | 0.000000 | 0 | 0 |
| query end | 0.000004 | 0.000000 | 0.000000 | 0 | 0 |
| closing tables | 0.000011 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000073 | 0.000000 | 0.000000 | 0 | 0 |
| removing tmp table | 0.000006 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000008 | 0.000000 | 0.000000 | 0 | 0 |
| Waiting for query cache lock | 0.000003 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000290 | 0.000000 | 0.000000 | 0 | 0 |
| Waiting for query cache lock | 0.000007 | 0.000000 | 0.000000 | 0 | 0 |
| freeing items | 0.000003 | 0.000000 | 0.000000 | 0 | 0 |
| storing result in query cache | 0.000005 | 0.000000 | 0.000000 | 0 | 0 |
| logging slow query | 0.000003 | 0.000000 | 0.000000 | 0 | 0 |
| logging slow query | 0.000068 | 0.000000 | 0.000000 | 0 | 8 |
| cleaning up | 0.000007 | 0.000000 | 0.000000 | 0 | 0 |
+--------------------------------+----------+----------+------------+--------------+

减少不必要的group by字段(二)