執行alter system flush buffer_cache一定會產生檢查點嗎？

LuiseDalian發表於2014-01-12

點選(此處)摺疊或開啟

  1. --檢視資料清空buffer cache
  2. --結論：沒有產生檢查點
  3. sys@TESTDB11>select * from scott.emp;

  5.      EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
  6. ---------- ---------- --------- ---------- --------- ---------- ---------- ----------
  7.       7369 SMITH CLERK 7902 17-DEC-80 800 20
  8.       7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
  9.       7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
  10.       7566 JONES MANAGER 7839 02-APR-81 2975 20
  11.       7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
  12.       7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
  13.       7782 CLARK MANAGER 7839 09-JUN-81 2450 10
  14.       7788 SCOTT ANALYST 7566 19-APR-87 3000 20
  15.       7839 KING PRESIDENT 17-NOV-81 5000 10
  16.       7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
  17.       7876 ADAMS CLERK 7788 23-MAY-87 1100 20
  18.       7900 JAMES CLERK 7698 03-DEC-81 950 30
  19.       7902 FORD ANALYST 7566 03-DEC-81 3000 20
  20.       7934 MILLER CLERK 7782 23-JAN-82 1300 10

  22. 14 rows selected.

  24. sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;

  26.      FILE# TS# CHECKPOINT_CHANGE#
  27. ---------- ---------- ------------------
  28.          1 0 2813140
  29.          2 1 2813140
  30.          3 2 2813140
  31.          4 4 2813140
  32.          5 6 2813140

  34. sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;

  36.      FILE# CHECKPOINT_CHANGE#
  37. ---------- ------------------
  38.          1 2813140
  39.          2 2813140
  40.          3 2813140
  41.          4 2813140
  42.          5 2813140

  44. sys@TESTDB11>alter system flush buffer_cache;

  46. System altered.

  48. sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;

  50.      FILE# TS# CHECKPOINT_CHANGE#
  51. ---------- ---------- ------------------
  52.          1 0 2813140
  53.          2 1 2813140
  54.          3 2 2813140
  55.          4 4 2813140
  56.          5 6 2813140

  58. sys@TESTDB11>alter system flush buffer_cache;

  60. System altered.

  62. sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;

  64.      FILE# CHECKPOINT_CHANGE#
  65. ---------- ------------------
  66.          1 2813140
  67.          2 2813140
  68.          3 2813140
  69.          4 2813140
  70.          5 2813140

  72. --更新資料，結論也沒有產生檢查點
  73. sys@TESTDB11>update scott.emp set sal = sal * 2;

  75. 14 rows updated.

  77. sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;

  79.      FILE# CHECKPOINT_CHANGE#
  80. ---------- ------------------
  81.          1 2813140
  82.          2 2813140
  83.          3 2813140
  84.          4 2813140
  85.          5 2813140

  87. sys@TESTDB11>alter system flush buffer_cache;

  89. System altered.

  91. sys@TESTDB11>select file#, checkpoint_change# from v$datafile_header;

  93.      FILE# CHECKPOINT_CHANGE#
  94. ---------- ------------------
  95.          1 2813140
  96.          2 2813140
  97.          3 2813140
  98.          4 2813140
  99.          5 2813140

  101. sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;

  103.      FILE# TS# CHECKPOINT_CHANGE#
  104. ---------- ---------- ------------------
  105.          1 0 2813140
  106.          2 1 2813140
  107.          3 2 2813140
  108.          4 4 2813140
  109.          5 6 2813140

  111. --手工產生檢查點
  112. sys@TESTDB11>alter system checkpoint;

  114. System altered.

  116. sys@TESTDB11>select file#, ts#, checkpoint_change# from v$datafile;

  118.      FILE# TS# CHECKPOINT_CHANGE#
  119. ---------- ---------- ------------------
  120.          1 0 2814217
  121.          2 1 2814217
  122.          3 2 2814217
  123.          4 4 2814217
  124.          5 6 2814217


來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/17013648/viewspace-1069756/，如需轉載，請註明出處，否則將追究法律責任。

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