Oracle分页查询优化

分页优化

在程序中涉及分页SQL的一些性能问题，这里总结一下：

1. 优化在查询列中有子查询时优化效果明显

耗时(s)	不分页	未处理前分页	处理后分页	提升
未排序	0.5	13.9	0.25	98%
排序	0.5	14.25	0.296	97.9%

• 不分页SQL

-- 耗时0.5s
SELECT ROWNUM ROWINDEX,              
       (select tbzt
          from t_dw_sbbg_bgsblb
         where bgsbid = t.obj_id
           and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
  from T_SB_ZWYC_JJ T
 WHERE 1 = 1
   AND exists (select bgsbid
          from t_dw_sbbg_bgsblb
         where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
           and bgsbid = t.obj_id)

• 未处理前的分页

-- 耗时13.9s
select *
  from (SELECT ROWNUM ROWINDEX,              
               (select tbzt
                  from t_dw_sbbg_bgsblb
                 where bgsbid = t.obj_id
                   and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
          from T_SB_ZWYC_JJ T
         WHERE 1 = 1
           AND exists
         (select bgsbid
                  from t_dw_sbbg_bgsblb
                 where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
                   and bgsbid = t.obj_id))
 WHERE ROWINDEX > 20
   AND ROWINDEX <= 40

• 处理后的分页

--耗时 0.25
select *
  from (SELECT ROWNUM ROWINDEX,               
               (select tbzt
                  from t_dw_sbbg_bgsblb
                 where bgsbid = t.obj_id
                   and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
          from T_SB_ZWYC_JJ T
         WHERE 1 = 1
           AND exists
         (select bgsbid
                  from t_dw_sbbg_bgsblb
                 where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
                   and bgsbid = t.obj_id) and ROWNUM<= 40 )
 WHERE ROWINDEX > 20

排序

• 不分页

-- 0.5
SELECT ROWNUM ROWINDEX,              
       (select tbzt
          from t_dw_sbbg_bgsblb
         where bgsbid = t.obj_id
           and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
  from T_SB_ZWYC_JJ T
 WHERE 1 = 1
   AND exists (select bgsbid
          from t_dw_sbbg_bgsblb
         where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
           and bgsbid = t.obj_id)
           order by obj_id

• 未处理

--14.25s
select *
  from (select ROWNUM ROWINDEX, tbzt from (SELECT               
               (select tbzt
                  from t_dw_sbbg_bgsblb
                 where bgsbid = t.obj_id
                   and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
          from T_SB_ZWYC_JJ T
         WHERE 1 = 1
           AND exists
         (select bgsbid
                  from t_dw_sbbg_bgsblb
                 where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
                   and bgsbid = t.obj_id) order by OBJ_ID))
 WHERE ROWINDEX > 20
   AND ROWINDEX <= 40

• 处理后

--0.296s
select *
  from ( select ROWNUM ROWINDEX, tbzt from (SELECT               
               (select tbzt
                  from t_dw_sbbg_bgsblb
                 where bgsbid = t.obj_id
                   and bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb') tbzt
          from T_SB_ZWYC_JJ T
         WHERE 1 = 1
           AND exists
         (select bgsbid
                  from t_dw_sbbg_bgsblb
                 where bgsqdid = '47c3514c-f8ba-4c13-8262-fb3553157aeb'
                   and bgsbid = t.obj_id)) where 1=1 and ROWNUM<= 40 )
 WHERE ROWINDEX > 20

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