你能帮我优化下面的联盟所有查询吗? 任何想法从哪里开始? 详情: SQL计划显示优化联盟所有SQL
| 7 | TABLE ACCESS FULL | DELAY_DATE | 17533 | 171K | 25(0)| 00:00:01 |
| 8 | TABLE ACCESS FULL |空间| 25879 | 454K | 298(1)| 00:00:04 |
| 16 | MERGE加入CARTESIAN | | 17533 | 273K | 28(4)| 00:00:01 |
这些潜在的问题是?
SELECT delay_reason_desc, delay_start_date, delay_end_date, delay_reason_code
FROM delay_date dd
LEFT JOIN delay_reason dr
ON dr.delay_reason_id=dd.delay_reason_id
LEFT JOIN delay_interval di
ON di.delay_interval_id=dr.delay_interval_id
LEFT JOIN vacancy v
ON v.vacancy_id=dd.vacancy_id
WHERE dr.delay_reason_active_ind='Y'
--AND dd.vacancy_id=p_vacancy_id
AND delay_start_date >= vacancy_fpps_received_date
AND delay_end_date <= vacancy_open_date
AND delay_interval_code=1
UNION ALL
SELECT delay_reason_desc, delay_start_date, delay_end_date, delay_reason_code
FROM delay_date dd
LEFT JOIN delay_reason dr
ON dr.delay_reason_id=dd.delay_reason_id
LEFT JOIN delay_interval di
ON di.delay_interval_id=dr.delay_interval_id
LEFT JOIN vacancy v
ON v.vacancy_id=dd.vacancy_id
WHERE dr.delay_reason_active_ind='Y'
--AND dd.vacancy_id=p_vacancy_id
AND delay_start_date >= vacancy_open_date
AND delay_end_date <= vacancy_closed_date
AND delay_interval_code=2
你对这些表有什么指标? – 2013-03-01 16:49:28
你应该尝试养成为表名别名加上前缀的习惯。在这种情况下,列中列出了哪些表是合理的,但它更强大,并且可以帮助阅读并包含它们。 – 2013-03-02 07:05:30