优化联合所有SQL [英] Optimize Union All SQL

问题描述

您能帮助我优化以下所有联合查询"吗? 知道从哪里开始吗? 细节: SQL计划显示

Could you help me optimize the following Union All Query? Any idea where to start? Details: SQL Plan shows

| 7 |表访问已满| DELAY_DATE | 17533 | 171K | 25(0)| 00:00:01 |
| 8 |表访问已满|空缺| 25879 | 454K | 298(1)| 00:00:04 |

| 7 | TABLE ACCESS FULL | DELAY_DATE | 17533 | 171K| 25 (0)| 00:00:01 |
| 8 | TABLE ACCESS FULL | VACANCY | 25879 | 454K| 298 (1)| 00:00:04 |

| 16 |合并联接笛卡尔| | 17533 | 273K | 28(4)| 00:00:01 |

| 16 | MERGE JOIN CARTESIAN | | 17533 | 273K| 28 (4)| 00:00:01 |

这些潜在的问题吗?

 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

推荐答案

如何解决-可能快两倍?

How about this -- could be as much as twice as fast:

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 ((delay_start_date >= vacancy_fpps_received_date
         AND delay_end_date <= vacancy_open_date
         AND delay_interval_code=1)
    OR  (delay_start_date >= vacancy_open_date
          AND delay_end_date <= vacancy_closed_date
          AND delay_interval_code=2))

这篇关于优化联合所有SQL的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！