SQL> set autotrace on
SQL> select employee_id from employees where rownum<10;
EMPLOYEE_ID
-----------
100
101
102
103
104
105
106
107
108
已选择9行。
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT ptimizer=CHOOSE (Cost=1 Card=9 Bytes=321)
1 0 COUNT (STOPKEY)
2 1 INDEX (FULL SCAN) OF 'EMP_EMP_ID_PK' (UNIQUE) (Cost=1 Ca
rd=107 Bytes=321)
Statistics
----------------------------------------------------------
7 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
483 bytes sent via SQL*Net to client
503 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
9 rows processed
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