需要有关重新编写此查询的指导

Question

当前方案=>我们有一个在产品集群上运行的查询。 此查询仅从1个表和另一个嵌套表（嵌套的联接）之间的联接中选择3个字段，然后在最后执行groupby，但在生产中运行了2个小时，并在该联接中命中了一个巨大表

查询：

INSERT OVERWRITE TABLE mstr_wrk.final_acct_data 
    SELECT
       a0,
       a1,
       a2,
       a3 
    FROM
                   (
                  SELECT
                 t1.a0 as a0 
                  FROM
                 (
                    SELECT
                       t1.a0 as a0 
                    FROM
                       (
                      SELECT
                         CAST(t1.acct_id AS STRING) as a0 
                      FROM
                         mstr_wrk.cust_xref t1
                       )
                       t1 
                    GROUP BY
                       t1.a0
                 )
                 t1
               )
       tab1 
       RIGHT OUTER JOIN
              (
             SELECT
              a0,
              a1,
              a2 
             FROM
                (
                   SELECT
        (
                  CASE
                     WHEN
                    1 = t1.a1 
                     THEN
                    t1.a0 
                     ELSE
                    CAST(NULL AS TIMESTAMP) 
                  END
        ) as a0, UDFcalldate('TRUNC', UDFcalldate('ADD_TO_DATE', 
                  (
                     CASE
                    WHEN
                       1 = t1.a1 
                    THEN
                       t1.a0 
                    ELSE
                       CAST(NULL AS TIMESTAMP) 
                     END
                  )
        , 'D', - 1), 'DD') as a1 
                   FROM
                  (
                     SELECT
                    MAX(t1.a0) as a0,
                    MAX(t1.a1) as a1 
                     FROM
                    (
                       SELECT
                          load_audit.run_ts as a0,
                          1 as a1 
                       FROM
                          mstr_wrk.load_audit 
                       WHERE
                          val_name = 'card_stg'
                    )
                    t1
                  )
                  t1
                )
                tab4 
                JOIN
                   (
                  SELECT
                     CAST(t1.acct_cd AS STRING) as a0,
                     CAST(t1.h_acct_cd AS STRING) as a1,
                     CAST(t1.acct_num AS STRING) as a2,
                     CAST(t1.load_dt AS TIMESTAMP) as a3,
                     t1.ts as a4 
                  FROM
                     mstr_work.acct_crd t1
                   )
                 tab3 
             WHERE
                (
                   tab4.a0 < tab3.a4
                )
                AND 
                (
                   tab4.a1 <= tab3.a3
                )
              )
          tab2 
          ON (tab1.a0 = tab2.a1) 
    WHERE
       1 = 
       (
          CASE
         WHEN
            tab1.a0 IS NULL 
         THEN
            1 
         ELSE
            0 
          END
       )
    GROUP BY
       tab2.a0, tab2.a1, tab2.a2

我尝试过的- 我试图启用CBO和矢量化以及ppd，但是没有运气 我在这里看不到任何小桌子，因此无法尝试地图侧连接 看起来像交叉联接的联接之一可以转换为内部联接 但是无论如何，我可以在这里尝试CTE

请求- 请指导我如何解决它 有没有更好的方法来重写此查询。