调优中发现的问题 “外连接不走索引”
SQL> set autotrace on
SQL> set timing on
SQL> select mgr.ma_id,mgr.ma_number,mgr.corp_id,mgr.passwd,c.corp_number,nvl2(c.
corp_id,1,0) status
2 from MGR_ACCOUNT mgr,CORP c
3 where mgr.ma_id=c.ma_id(+)[/COLOR] ;
已选择60行。
已用时间: 00: 00: 00.03
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=5 Card=59 Bytes=3481
)
1 0 HASH JOIN (OUTER) (Cost=5 Card=59 Bytes=3481)
2 1 TABLE ACCESS (FULL) OF 'MGR_ACCOUNT' (Cost=2 Card=59 Byt
es=2301)
3 1 TABLE ACCESS (FULL) OF 'CORP' (Cost=2 Card=11 Bytes=220)
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
15 consistent gets
0 physical reads
0 redo size
2723 bytes sent via SQL*Net to client
528 bytes received via SQL*Net from client
5 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
60 rows processed
挺郁闷
MGR_ACCOUNT(ma_id)和CORP(ma_id)都有索引
而且也analyze 过两个表,CBO还是不走索引.
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