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  • 什么情况下走sort merge join

    SQL_ID  cqsz37256v36j, child number 1
    -------------------------------------
    INSERT /*+append*/ INTO TMP_ACCT_AF NOLOGGING ( DATA_DATE , ACCT_NO , ACCT_ORD , ACCT_NO_PK , ACCT_BAL , D_CMP_BAL ,
    M_CMP_BAL , Y_CMP_BAL , FLAG , ACCT_FLAG , TERM , TERM_FLAG , CUR_CODE , CUR_NAME , SUB_CODE , CUST_NO , CUST_TYPE ,
    CUST_NAME , BANK_CORP_CODE , BRAN_NAME , MGR_CODE , MGR_NAME , OPEN_DATE , FIX_BAL , DIV_FIX_FLAG , ADJUST_AMT ,
    ADJUST_AMT_AF , Y_AVG_AF , Y_ADD_AF , ACCT_INTR , SIM_PROFIT , SEPA_POR , PRI , BRAN_CODE , UNIT1_CODE , UNIT2_CODE ,
    UNIT3_CODE , DEPT1_CODE , INTR_RATE , DUE_DATE ) SELECT /*+use_merge(t1 t2)parallel(t1 16) use_hash(t1 t3)*/ DATA_DATE,
    ACCT_NO, ACCT_ORD, ACCT_NO_PK, ACCT_BAL, D_CMP_BAL, M_CMP_BAL, Y_CMP_BAL, FLAG, ACCT_FLAG, TERM, TERM_FLAG, CUR_CODE,
    CUR_NAME, SUB_CODE, CUST_NO, CUST_TYPE, CUST_NAME, BANK_CORP_CODE, BRAN_NAME, NVL(T3.MGR_CODE, T1.MGR_CODE), T1.MGR_NAME,
    OPEN_DATE, FIX_BAL, DIV_FIX_FLAG, ADJUST_AMT, ADJUST_AMT_AF, Y_AVG_AF, Y_ADD_AF, ACCT_INTR, SIM_PROFIT, SEPA_POR, PRI,
    T1.BRAN_CODE, T2.UNIT1_CODE, T2.UNIT2_CODE, T1.BRAN_CODE
     
    Plan hash value: 1366440900
     
    ------------------------------------------------------------------------------------------------------------------------------------
    | Id  | Operation                        | Name               | Rows  | Bytes | Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
    ------------------------------------------------------------------------------------------------------------------------------------
    |   0 | INSERT STATEMENT                 |                    |       |       |    24 (100)|          |        |      |            |
    |   1 |  LOAD AS SELECT                  |                    |       |       |            |          |        |      |            |
    |   2 |   PX COORDINATOR                 |                    |       |       |            |          |        |      |            |
    |   3 |    PX SEND QC (RANDOM)           | :TQ10005           |     1 |   672 |    24  (30)| 00:00:01 |  Q1,05 | P->S | QC (RAND)  |
    |   4 |     VIEW                         |                    |     1 |   672 |    24  (30)| 00:00:01 |  Q1,05 | PCWP |            |
    |   5 |      SORT UNIQUE                 |                    |     1 |   650 |    24  (30)| 00:00:01 |  Q1,05 | PCWP |            |
    |   6 |       PX RECEIVE                 |                    |     1 |   650 |    23  (27)| 00:00:01 |  Q1,05 | PCWP |            |
    |   7 |        PX SEND HASH              | :TQ10004           |     1 |   650 |    23  (27)| 00:00:01 |  Q1,04 | P->P | HASH       |
    |*  8 |         HASH JOIN OUTER          |                    |     1 |   650 |    23  (27)| 00:00:01 |  Q1,04 | PCWP |            |
    |   9 |          PX RECEIVE              |                    |     1 |   622 |    18  (28)| 00:00:01 |  Q1,04 | PCWP |            |
    |  10 |           PX SEND HASH           | :TQ10003           |     1 |   622 |    18  (28)| 00:00:01 |  Q1,03 | P->P | HASH       |
    |  11 |            MERGE JOIN OUTER      |                    |     1 |   622 |    18  (28)| 00:00:01 |  Q1,03 | PCWP |            |
    |  12 |             SORT JOIN            |                    |     1 |   601 |     3  (34)| 00:00:01 |  Q1,03 | PCWP |            |
    |  13 |              PX RECEIVE          |                    |     1 |   601 |     2   (0)| 00:00:01 |  Q1,03 | PCWP |            |
    |  14 |               PX SEND HASH       | :TQ10002           |     1 |   601 |     2   (0)| 00:00:01 |  Q1,02 | P->P | HASH       |
    |  15 |                PX BLOCK ITERATOR |                    |     1 |   601 |     2   (0)| 00:00:01 |  Q1,02 | PCWC |            |
    |* 16 |                 TABLE ACCESS FULL| TMP_ACCT_AF2       |     1 |   601 |     2   (0)| 00:00:01 |  Q1,02 | PCWP |            |
    |* 17 |             SORT JOIN            |                    |  8158 |   167K|    15  (27)| 00:00:01 |  Q1,03 | PCWP |            |
    |  18 |              BUFFER SORT         |                    |       |       |            |          |  Q1,03 | PCWC |            |
    |  19 |               PX RECEIVE         |                    |  8158 |   167K|    12   (9)| 00:00:01 |  Q1,03 | PCWP |            |
    |  20 |                PX SEND HASH      | :TQ10000           |  8158 |   167K|    12   (9)| 00:00:01 |        | S->P | HASH       |
    |  21 |                 TABLE ACCESS FULL| S_PM_MGR_DEPT_RELA |  8158 |   167K|    12   (9)| 00:00:01 |        |      |            |
    |  22 |          BUFFER SORT             |                    |       |       |            |          |  Q1,04 | PCWC |            |
    |  23 |           PX RECEIVE             |                    |  3902 |   106K|     5  (20)| 00:00:01 |  Q1,04 | PCWP |            |
    |  24 |            PX SEND HASH          | :TQ10001           |  3902 |   106K|     5  (20)| 00:00:01 |        | S->P | HASH       |
    |* 25 |             INDEX FAST FULL SCAN | MGR_DEPT_RELA_IDX2 |  3902 |   106K|     5  (20)| 00:00:01 |        |      |            |
    ------------------------------------------------------------------------------------------------------------------------------------
     
    Predicate Information (identified by operation id):
    ---------------------------------------------------
     
       8 - access("T1"."MGR_CODE"="T3"."MGR_CODE")
      16 - access(:Z>=:Z AND :Z<=:Z)
      17 - access("T1"."BRAN_CODE"="T2"."UNIT3_CODE")
           filter("T1"."BRAN_CODE"="T2"."UNIT3_CODE")
      25 - filter("T3"."DEPT1_CODE"<>'999999999')
     
     
     TMP_ACCT_AF2 T1
     
    (SELECT DISTINCT T2.UNIT3_CODE, T2.UNIT2_CODE, T2.UNIT1_CODE
                     FROM S_PM_MGR_DEPT_RELA T2) T2
    T2是个大表
    
    
     
     
    S_PM_MGR_DEPT_RELA T3
     
     
     
    T1 和 T2 进行 sort merge join 在 T1和 T3进行 hash join,直接导致temp被耗尽
     
     
     
     (SELECT /*+use_merge(t1 t2)parallel(t1 16) use_hash(t1 t3)*/
       DATA_DATE,
       ACCT_NO,
       ACCT_ORD,
       ACCT_NO_PK,
       ACCT_BAL,
       D_CMP_BAL,
       M_CMP_BAL,
       Y_CMP_BAL,
       FLAG,
       ACCT_FLAG,
       TERM,
       TERM_FLAG,
       CUR_CODE,
       CUR_NAME,
       SUB_CODE,
       CUST_NO,
       CUST_TYPE,
       CUST_NAME,
       BANK_CORP_CODE,
       BRAN_NAME,
       NVL(T3.MGR_CODE, T1.MGR_CODE),
       T1.MGR_NAME,
       OPEN_DATE,
       FIX_BAL,
       DIV_FIX_FLAG,
       ADJUST_AMT,
       ADJUST_AMT_AF,
       Y_AVG_AF,
       Y_ADD_AF,
       ACCT_INTR,
       SIM_PROFIT,
       SEPA_POR,
       PRI,
       T1.BRAN_CODE,
       T2.UNIT1_CODE,
       T2.UNIT2_CODE,
       T1.BRAN_CODE AS UNIT3_CODE,
       NVL(T3.DEPT1_CODE, '999999999'),
       T1.INTR_RATE,
       T1.DUE_DATE
        FROM TMP_ACCT_AF2 T1
        LEFT JOIN S_PM_MGR_DEPT_RELA T3
          ON T1.MGR_CODE = T3.MGR_CODE
         AND T3.DEPT1_CODE <> '999999999'
        LEFT JOIN (SELECT DISTINCT T2.UNIT3_CODE, T2.UNIT2_CODE, T2.UNIT1_CODE
                     FROM S_PM_MGR_DEPT_RELA T2) T2
          ON T1.BRAN_CODE = T2.UNIT3_CODE)
     
    Plan hash value: 4109009912
     
    -----------------------------------------------------------------------------------------------------------------------------------------
    | Id  | Operation                     | Name               | Rows  | Bytes |TempSpc| Cost (%CPU)| Time     |    TQ  |IN-OUT| PQ Distrib |
    -----------------------------------------------------------------------------------------------------------------------------------------
    |   0 | INSERT STATEMENT              |                    |   142M|    28G|       |   629  (69)| 00:00:02 |        |      |            |
    |   1 |  LOAD AS SELECT               | TMP_ACCT_AF        |       |       |       |            |          |        |      |            |
    |   2 |   PX COORDINATOR              |                    |       |       |       |            |          |        |      |            |
    |   3 |    PX SEND QC (RANDOM)        | :TQ10002           |   142M|    28G|       |   629  (69)| 00:00:02 |  Q1,02 | P->S | QC (RAND)  |
    |   4 |     MERGE JOIN OUTER          |                    |   142M|    28G|       |   629  (69)| 00:00:02 |  Q1,02 | PCWP |            |
    |   5 |      SORT JOIN                |                    |  1500K|   208M|   450M|   254  (27)| 00:00:01 |  Q1,02 | PCWP |            |
    |*  6 |       HASH JOIN RIGHT OUTER   |                    |  1500K|   208M|       |   225  (17)| 00:00:01 |  Q1,02 | PCWP |            |
    |   7 |        BUFFER SORT            |                    |       |       |       |            |          |  Q1,02 | PCWC |            |
    |   8 |         PX RECEIVE            |                    |  3902 | 62432 |       |     5  (20)| 00:00:01 |  Q1,02 | PCWP |            |
    |   9 |          PX SEND BROADCAST    | :TQ10000           |  3902 | 62432 |       |     5  (20)| 00:00:01 |        | S->P | BROADCAST  |
    |* 10 |           INDEX FAST FULL SCAN| MGR_DEPT_RELA_IDX2 |  3902 | 62432 |       |     5  (20)| 00:00:01 |        |      |            |
    |  11 |        PX BLOCK ITERATOR      |                    |  1407K|   174M|       |   217  (16)| 00:00:01 |  Q1,02 | PCWC |            |
    |  12 |         TABLE ACCESS FULL     | TMP_ACCT_AF2       |  1407K|   174M|       |   217  (16)| 00:00:01 |  Q1,02 | PCWP |            |
    |* 13 |      SORT JOIN                |                    |  7315 |   471K|       |    17  (36)| 00:00:01 |  Q1,02 | PCWP |            |
    |  14 |       BUFFER SORT             |                    |       |       |       |            |          |  Q1,02 | PCWC |            |
    |  15 |        PX RECEIVE             |                    |  7315 |   471K|       |    15  (27)| 00:00:01 |  Q1,02 | PCWP |            |
    |  16 |         PX SEND BROADCAST     | :TQ10001           |  7315 |   471K|       |    15  (27)| 00:00:01 |        | S->P | BROADCAST  |
    |  17 |          VIEW                 |                    |  7315 |   471K|       |    15  (27)| 00:00:01 |        |      |            |
    |  18 |           SORT UNIQUE         |                    |  7315 |   150K|       |    15  (27)| 00:00:01 |        |      |            |
    |  19 |            TABLE ACCESS FULL  | S_PM_MGR_DEPT_RELA |  8158 |   167K|       |    12   (9)| 00:00:01 |        |      |            |
    -----------------------------------------------------------------------------------------------------------------------------------------
     
    Predicate Information (identified by operation id):
    ---------------------------------------------------
     
       6 - access("T1"."MGR_CODE"="T3"."MGR_CODE"(+))
      10 - filter("T3"."DEPT1_CODE"(+)<>'999999999')
      13 - access("T1"."BRAN_CODE"="T2"."UNIT3_CODE"(+))
           filter("T1"."BRAN_CODE"="T2"."UNIT3_CODE"(+))
     
     正确关联顺序为T1 和 T3进行HASH JOIN  在通过T1和T2 进行sort merge join
    
    
    
    这里为什么走sort merge join
    
    
    SELECT DISTINCT T2.UNIT3_CODE, T2.UNIT2_CODE, T2.UNIT1_CODE
                     FROM S_PM_MGR_DEPT_RELA T2
    
    因为distinct sort uniqe 已经排序了
    
    
    
    
    1.使用HINT
    2.非等值JOIN
    3.有一个表或者2个表都已经排序好了
    4.JOIN列有索引,对索引进行INDEX FULL SCAN(请自己复习前文的访问路径)返回有序的结 
      果,再和另外的表进行JOIN。
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  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13348746.html
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