子查询解嵌套not in 无法展开改写
SQL> explain plan for select *
from OPS$CZTEST1.SAVJ_ATOMJOURBAK
where ((list_flag = '1' and prt_flag = '0') and
acct_no not in
(select acct_no
from OPS$CZTEST1.savb_basicinfo1
where ((card_no is not null and base_acct_no is null) or
(book_flag = '1' and bus_code = 21)))); 2 3 4 5 6 7 8
Explained.
SQL> select * from table(dbms_xplan.display());
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 3909253513
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 54953 | 18M| 594M (1) |999:59:59 |
|* 1 | FILTER | | | | | |
|* 2 | TABLE ACCESS FULL | SAVJ_ATOMJOUR0 | 54954 | 18M| 1042 (3) | 00:00:13 |
|* 3 | TABLE ACCESS FULL | SAVB_BASICINFO1 | 1 | 73 | 11220 (1) | 00:02:15 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter( NOT EXISTS (SELECT /*+ */ 0 FROM
"OPS$CZTEST1"."SAVB_BASICINFO1" "SAVB_BASICINFO1" WHERE ("BASE_ACCT_NO" IS
NULL AND "CARD_NO" IS NOT NULL OR "BUS_CODE"=21 AND "BOOK_FLAG"='1') AND
LNNVL("ACCT_NO"<>:B1)))
2 - filter("PRT_FLAG"='0' AND "LIST_FLAG"='1')
3 - filter(("BASE_ACCT_NO" IS NULL AND "CARD_NO" IS NOT NULL OR
"BUS_CODE"=21 AND "BOOK_FLAG"='1') AND LNNVL("ACCT_NO"<>:B1))
21 rows selected.
可以看到这里:
( NOT EXISTS (SELECT /*+ */ 0 FROM
"OPS$CZTEST1"."SAVB_BASICINFO1" "SAVB_BASICINFO1" WHERE ("BASE_ACCT_NO" IS
NULL AND "CARD_NO" IS NOT NULL OR "BUS_CODE"=21 AND "BOOK_FLAG"='1') AND
LNNVL("ACCT_NO"<>:B1)))
子查询没有展开,FILTER 循环类似于NL循环,会导致表SAVB_BASICINFO1访问多次,not in 可以改写成左关联的形式,改写如下:
SQL> explain plan for select count(*)
from OPS$CZTEST1.SAVJ_ATOMJOURBAK a,
(select acct_no
from OPS$CZTEST1.savb_basicinfo1
where (card_no is not null and base_acct_no is null)
or
(book_flag = '1' and bus_code = 21)) b
where a.list_flag = '1'
and a.prt_flag = '0'
and a.acct_no = b.acct_no(+)
and b.acct_no is null; 2 3 4 5 6 7 8 9 10 11
Explained.
SQL> select * from table(dbms_xplan.display());
PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 4182698075
-----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 110 | | 13060 (1)| 00:02:37 |
| 1 | SORT AGGREGATE | | 1 | 110 | | | |
|* 2 | HASH JOIN ANTI | | 1 | 110 | 2632K| 13060 (1)| 00:02:37 |
|* 3 | TABLE ACCESS FULL | SAVJ_ATOMJOUR0 | 54954 | 1985K| | 1041 (2)| 00:00:13 |
|* 4 | TABLE ACCESS FULL | SAVB_BASICINFO1 | 166K| 11M| | 11216 (1)| 00:02:15 |
-----------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("ACCT_NO"="ACCT_NO")
3 - filter("PRT_FLAG"='0' AND "LIST_FLAG"='1')
4 - filter("BASE_ACCT_NO" IS NULL AND "CARD_NO" IS NOT NULL OR "BUS_CODE"=21 AND
"BOOK_FLAG"='1')
19 rows selected.