我运行两个查询:
SELECT * FROM T_PUB_ITEMVALUE WHERE TIME LIKE '200307'
Execution Plan
----------------------------------------------------------
0SELECT STATEMENT Optimizer=CHOOSE (Cost=166 Card=34244 Bytes
=856100)
10 TABLE ACCESS (BY INDEX ROWID) OF 'T_PUB_ITEMVALUE' (Cost=1
66 Card=34244 Bytes=856100)
21 INDEX (RANGE SCAN) OF 'IDX_PUB_ITEMVALUE_TIME' (NON-UNIQ
UE) (Cost=70 Card=34244)
SELECT * FROM T_PUB_ITEMVALUE WHERE TIME = '200307'
Execution Plan
----------------------------------------------------------
0SELECT STATEMENT Optimizer=CHOOSE (Cost=1615 Card=146108 Byt
es=3652700)
10 TABLE ACCESS (FULL) OF 'T_PUB_ITEMVALUE' (Cost=1615 Card=1
