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--查看数据清空buffer cache
--结论：没有产生检查点
sys@TESTDB11>select * from scott.emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
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
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
14 rows selected.
sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;
FILE# TS# CHECKPOINT_CHANGE#
---------- ---------- ------------------
1 0 2813140
2 1 2813140
3 2 2813140
4 4 2813140
5 6 2813140
sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;
FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 2813140
2 2813140
3 2813140
4 2813140
5 2813140
sys@TESTDB11>alter system flush buffer_cache;
System altered.
sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;
FILE# TS# CHECKPOINT_CHANGE#
---------- ---------- ------------------
1 0 2813140
2 1 2813140
3 2 2813140
4 4 2813140
5 6 2813140
sys@TESTDB11>alter system flush buffer_cache;
System altered.
sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;
FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 2813140
2 2813140
3 2813140
4 2813140
5 2813140
--更新数据，结论也没有产生检查点
sys@TESTDB11>update scott.emp set sal = sal * 2;
14 rows updated.
sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;
FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 2813140
2 2813140
3 2813140
4 2813140
5 2813140
sys@TESTDB11>alter system flush buffer_cache;
System altered.
sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;
FILE# CHECKPOINT_CHANGE#
---------- ------------------
1 2813140
2 2813140
3 2813140
4 2813140
5 2813140
sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;
FILE# TS# CHECKPOINT_CHANGE#
---------- ---------- ------------------
1 0 2813140
2 1 2813140
3 2 2813140
4 4 2813140
5 6 2813140
--手工产生检查点
sys@TESTDB11>alter system checkpoint;
System altered.
sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;
FILE# TS# CHECKPOINT_CHANGE#
---------- ---------- ------------------
1 0 2814217
2 1 2814217
3 2 2814217
4 4 2814217
5 6 2814217

ITPub博客

执行alter system flush buffer_cache一定会产生检查点吗？

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