Sql 解码。并且假设驱动表应该是DISB_A（从DISB_B驱动查询要容易得多，所以让我们知道针对DISB_B的独立过滤器是否能有效地减少访问的行数）。我会将查询重写为（可能有拼写错误）：

并创建以下索引：

create index DISB_A_idx_v on DISB_A (v_id, effdate);
create index DISB_A_idx_code on DISB_A (code, effdate);
create index DISB_B_idx on DISB_B (nd_id,a_id,dsba_id);

---

如果这仍然是相对缓慢的，那么它将有助于有一些反馈如何选择这些过滤器真的是。看看如何在计划内获取行源代码执行统计信息（的第4点），并将该信息包含在原始问题中。

您之前问了基本相同的问题（），答案建议使用两个索引，这两个索引都不在本表中。我建议你删除这个问题，直到你尝试这个问题的答案。你可以看到，我已经在问题本身添加了索引。我还包括了CREATEINDEX语句。我没有看到前两列是

nd\u id

和

a\u id

的索引。同样，对于第二个推荐索引，您不认为我不需要为disb_b表添加索引，因为成本/索引利用率在那里是正确的。根据我的说法（我可能错了），问题在于解散一张桌子。因此，不应该将重点放在表A中的索引而不是表B中的索引？成本是使用您的查询、统计和优化器数学进行的估计。它有时最终将无法代表现实。

xxxxxxxx

是什么意思？根据您的计划谓词判断，您在这里输入了一个文本值，这使得您的解码无法索引-您应该考虑重写它（对于优化器来说，解码也很难估计）。如果基数估计值是合理的（并且表

DISB_a

中只有少量的行与谓词匹配），那么通过重写，可以正确使用索引，从而大大提高性能。这实际上首先会复制记录。上面写的逻辑和解码不一样。Decode将选择v_id（如果匹配）或状态代码（如果完整）。但是我们在上面的解决方案中从这两个条件中获取记录。我不这么认为，如果v_id匹配（隐式要求两者都不为null），则第一部分将成功，如果v_id为null且输入为null，则第二部分将成功，如果代码完整且v_id与输入不匹配（或者如果只有一个为null）。您是否有导致双重计数的示例输入和数据？

INDEX_OWNER   INDEX_NAME  TABLE_OWNER TABLE_NAME    COLUMN_NAME    COLUMN_POSITION  COLUMN_LENGTH   CHAR_LENGTH DESCEND COLLATED_COLUMN_ID
-------------------------------------------------------------------------------------------------------------------------------------
DEVL         DISB_B_INDX1   DEVL       DISB_B        DSBA_ID        1                  22                0        ASC   
DEVL         DISB_B_INDX1   DEVL       DISB_B        SEQNBR         2                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        DSBA_ID        1                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        ND_ID          2                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        A_ID           3                  13                13       ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        DIO_ID         4                  6                 6        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        AIO_QUAL       5                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        DMT_CODE       6                  3                 3        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        DMT_SEQNBR     7                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        ORDER_SEQNBR   8                  22                0        ASC   
DEVL         DISB_B_PRIME   DEVL       DISB_B        NBR            9                  20                20       ASC   

SQL> explain plan 
     for 
SELECT SUM ( NVL ( dd.req_amt , 0 ) )
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = xxxxxxxx
AND dd.a_id = 'xx-xx'
AND DECODE (db.v_id , xxxxxxxxx , 'COMPLETE' , db.code ) = 'COMPLETE'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE; 
 Explained.

 Elapsed: 00:00:00.04
 SQL> select * from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
Plan hash value: 4272128008
--------------------------------------------------------------------------------------------------
| Id  | Operation                      | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT               |                 |     1 |    58 | 62271   (1)| 00:00:03 |
|   1 |  SORT AGGREGATE                |                 |     1 |    58 |            |          |
|*  2 |   FILTER                       |                 |       |       |            |          |
|   3 |    NESTED LOOPS                |                 |     1 |    58 | 62271   (1)| 00:00:03 |
|   4 |     NESTED LOOPS               |                 |    10 |    58 | 62271   (1)| 00:00:03 |
|*  5 |      TABLE ACCESS STORAGE FULL | DISB_A          |    10 |   300 | 62231   (1)| 00:00:03 |
|*  6 |      INDEX RANGE SCAN          | DISB_B_PRIME    |     1 |       |     3   (0)| 00:00:01 |
|   7 |     TABLE ACCESS BY INDEX ROWID| DISB_B          |     1 |    28 |     4   (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter(SYSDATE@!>=TRUNC(SYSDATE@!,'fmyear'))
   5 - storage(DECODE("DB"."EV_ID",1263421688,'COMPLETE',"DB"."STATUS_CODE")='COMPLETE'
              AND "DB"."EFFDATE">=TRUNC(SYSDATE@!,'fmyear') AND "DB"."EFFDATE"<=SYSDATE@!)
       filter(DECODE("DB"."EV_ID",1263421688,'COMPLETE',"DB"."STATUS_CODE")='COMPLETE'
              AND "DB"."EFFDATE">=TRUNC(SYSDATE@!,'fmyear') AND "DB"."EFFDATE"<=SYSDATE@!)
   6 - access("DB"."ID"="DD"."DSBA_ID" AND "DD"."IND_ID"=20972265 AND
              "DD"."GA_ID"='150563-01')

25 rows selected.

Elapsed: 00:00:00.02

SQL> SELECT SUM ( NVL ( dd.req_amt , 0 ) )
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = xxxxxxxx
AND dd.a_id = 'xx-xx'
AND DECODE (db.v_id , xxxxxxxxx , 'COMPLETE' , db.code ) = 'COMPLETE'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE; 

 SUM(NVL(DD.REQ_AMT,0))
 ______________________
             62500

  **1 row selected.
  Elapsed: 00:00:01.65**

 **CREATE INDEX DISB_A_INDX5 ON DISB_A (ID,IND_id,EV_ID,status_code,EFFDATE ASC) NOPARALLEL;**

 PLAN_TABLE_OUTPUT
 Plan hash value: 2535999045

-----------------------------------------------------------------------------------------------------
| Id  | Operation                        | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                 |                  |     1 |    58 | 18669   (1)| 00:00:01 |
|   1 |  SORT AGGREGATE                  |                  |     1 |    58 |            |          |
|*  2 |   FILTER                         |                  |       |       |            |          |
|   3 |    NESTED LOOPS                  |                  |     1 |    58 | 18669   (1)| 00:00:01 |
|   4 |     NESTED LOOPS                 |                  |    35 |    58 | 18669   (1)| 00:00:01 |
|*  5 |      INDEX STORAGE FAST FULL SCAN| DISB_A_INDX5     |    35 |  1050 | 18598   (1)| 00:00:01 |
|*  6 |      INDEX RANGE SCAN            | DISB_B_PRIME     |     1 |       |     3   (0)| 00:00:01 |
|   7 |     TABLE ACCESS BY INDEX ROWID  | DISB_B           |     1 |    28 |     4   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter(SYSDATE@!>=TRUNC(SYSDATE@!,'fmyear'))
   5 - storage(DECODE("DB"."EV_ID",1263421688,'COMPLETE',"DB"."STATUS_CODE")='COMPLETE' AND
              "DB"."EFFDATE"<=SYSDATE@! AND "DB"."EFFDATE">=TRUNC(SYSDATE@!,'fmyear'))
       filter(DECODE("DB"."EV_ID",1263421688,'COMPLETE',"DB"."STATUS_CODE")='COMPLETE' AND
              "DB"."EFFDATE"<=SYSDATE@! AND "DB"."EFFDATE">=TRUNC(SYSDATE@!,'fmyear'))
   6 - access("DB"."ID"="DD"."DSBA_ID" AND "DD"."IND_ID"=20972265 AND
              "DD"."GA_ID"='150563-01')

25 rows selected.

Elapsed: 00:00:00.03


SQL> SELECT SUM ( NVL ( dd.req_amt , 0 ) )
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = xxxxxxxx
AND dd.a_id = 'xx-xx'
AND DECODE (db.v_id , xxxxxxxxx , 'COMPLETE' , db.code ) = 'COMPLETE'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE; 

SUM(NVL(DD.REQ_AMT,0))
______________________
                 62500

**1 row selected.
Elapsed: 00:00:05.45**

select sum(req_amt) 
from (
SELECT SUM ( dd.req_amt  ) req_amt
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = :xxxxxxxx
AND dd.a_id = 'xx-xx'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE
and db.v_id = :xxxxxxxxx 
union all
SELECT SUM ( dd.req_amt  ) req_amt
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = :xxxxxxxx
AND dd.a_id = 'xx-xx'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE
and (db.v_id is null and :xxxxxxxxx is null)
union all
SELECT SUM ( dd.req_amt  ) req_amt
FROM DISB_A db ,
     DISB_B dd
WHERE db.id = dd.dsba_id
AND dd.nd_id = :xxxxxxxx
AND dd.a_id = 'xx-xx'
AND db.effdate BETWEEN TRUNC ( SYSDATE , 'YEAR' ) AND SYSDATE
and  db.code = 'COMPLETE'
and  lnnvl(db.v_id = :xxxxxxxxx )
    )

create index DISB_A_idx_v on DISB_A (v_id, effdate);
create index DISB_A_idx_code on DISB_A (code, effdate);
create index DISB_B_idx on DISB_B (nd_id,a_id,dsba_id);