# 执行计划偏差（A）

+ SQL 语句文本:
+ 执行计划获取:
```
SELECT id, report_dt, user_id, avatarpath, interact_type, reward_type_id, show_name, reward_name, city_name, create_time, update_time, version
FROM
  report_interact_detail
WHERE
  report_dt = ‘' AND reward_type_id = ''
ORDER BY —
  winning_create_time DESC
LIMIT
  1; 

SELECT plan，plan_digest,digest_text
FROM
information_schema.statements_summary - - 或者 statements_summary_history
WHERE 
digest = '442f8f99f982cde1b561f15640c269067614d0a5b9efb5aaf23344749666d5a0';
```
-------------------------------------------------------------
```
SELECT
  id,
  report_dt,
  user_id,
  avatarpath,
  interact_type,
  reward_type_id,
  show_name,
  reward_name,
  city_name,
  create_time,
  update_time,
  version
FROM
  report_interact_detail
WHERE
  report_dt = ‘'
  AND reward_type_id = ''
ORDER BY
  winning_create_time DESC
LIMIT
  1;
```

SQL 中使用的是 Order by winning_create_time DESC，索引扫描使用 create_time 字段上的单列索引
```
select plan，plan_digest,digest_text
from information_schema.statements_summary / statements_summary_history
where digest='442f8f99f982cde1b561f15640c269067614d0a5b9efb5aaf23344749666d5a0';
```