重新收集统计信息

SQL> show user
USER is "SA"
SQL>

SQL> select last_analyzed from dba_tables where table_name='EMP' and owner='SA';

LAST_ANAL
---------
30-DEC-15

SQL> select * from emp;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
         1                                                                         11
         2                                                                         80
      7369 SMITH      CLERK           7902 17-DEC-80        800                    20
      7499 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
      7521 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
      7566 JONES      MANAGER         7839 02-APR-81       2975                    20
      7654 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
      7698 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
      7782 CLARK      MANAGER         7839 09-JUN-81       2450                    10
      7788 SCOTT      ANALYST         7566 19-APR-87       3000                    20
      7839 KING       PRESIDENT            17-NOV-81       5000                    10

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
      7844 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
      7876 ADAMS      CLERK           7788 23-MAY-87       1100                    20
      7900 JAMES      CLERK           7698 03-DEC-81        950                    30
      7902 FORD       ANALYST         7566 03-DEC-81       3000                    20
      7934 MILLER     CLERK           7782 23-JAN-82       1300                    10

16 rows selected.

SQL> select column_name,num_distinct from dba_tab_columns where table_name='EMP' and owner='SA';

COLUMN_NAME                    NUM_DISTINCT
------------------------------ ------------
EMPNO                                    14
ENAME                                    14
JOB                                       5
MGR                                       6
HIREDATE                                 13
SAL                                      12
COMM                                      4
DEPTNO                                    3

8 rows selected.

SQL> exec DBMS_STATS.GATHER_TABLE_STATS(ownname=>'SA',tabname=>'EMP',ESTIMATE_PERCENT=>1,method_opt=>'for all columns size 1',cascade=>true,force=>true,degree=>4);

PL/SQL procedure successfully completed.

SQL> select column_name,num_distinct from dba_tab_columns where table_name='EMP' and owner='SA';

COLUMN_NAME                    NUM_DISTINCT
------------------------------ ------------
EMPNO                                    16
ENAME                                    14
JOB                                       5
MGR                                       6
HIREDATE                                 13
SAL                                      12
COMM                                      4
DEPTNO                                    5

8 rows selected.

SQL>

SQL> select last_analyzed from dba_tables where table_name='EMP' and owner='SA';

LAST_ANAL
---------
03-JAN-16

SQL>

妈呀，怎么时间不对。。。我系统时间错了~~
SQL> !date
Sun Jan  3 19:20:58 CST 2016