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接手了一个新交接的库，alert日志频繁报告log file switch (checkpoint incomplete)事件
oracle文档解释：
Waiting for a log switch because the session cannot wrap into the next log. Wrapping cannot be performed because the checkpoint for that log has not completed.
查看redo日志信息:
SQL> select * from v$log; GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARCHIVED STATUS FIRST_CHANGE# FIRST_TIME NEXT_CHANGE# NEXT_TIME ---------- ---------- ---------- ---------- ---------- ---------- -------- ---------------- ------------- ----------- ------------ ----------- 1 1 19852 52428800 512 1 YES INACTIVE 179403613 7/27/2015 1 179417290 7/27/2015 1 2 1 19853 52428800 512 1 NO CURRENT 179417290 7/27/2015 1 281474976710 3 1 19851 52428800 512 1 YES INACTIVE 179393208 7/27/2015 1 179403613 7/27/2015 1 SQL> select * from v$logfile; GROUP# STATUS TYPE MEMBER IS_RECOVERY_DEST_FILE ---------- ------- ------- -------------------------------------------------------------------------------- --------------------- 3 ONLINE D:\APP\ADMINISTRATOR\ORADATA\YB\REDO03.LOG NO 2 ONLINE D:\APP\ADMINISTRATOR\ORADATA\YB\REDO02.LOG NO 1 ONLINE D:\APP\ADMINISTRATOR\ORADATA\YB\REDO01.LOG NO SQL>
查看切换频率:
SQL> select completion_time from v$archived_log order by 1 desc;
发现在系统繁忙时候，日志一分钟会切换好几次。
解决方案：
添加个日志组并将日志大小调整为100m
alter database add logfile group 4 (‘D:\APP\ADMINISTRATOR\ORADATA\YB\REDO04a.LOG ‘,‘D:\APP\ADMINISTRATOR\ORADATA\YB\REDO04b.LOG ‘) size 100M;
然后将其它三组redo日志的进行调整：删除已有日志组，然后重建（要将日志组调整到inactive状态后再操作）
alter database drop logfile group 3; alter database add logfile group 3 (‘D:\APP\ADMINISTRATOR\ORADATA\YB\REDO03a.LOG ‘,‘D:\APP\ADMINISTRATOR\ORADATA\YB\REDO03b.LOG ‘) size 100M;
...
log file switch (checkpoint incomplete)
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原文地址：http://www.cnblogs.com/abclife/p/4679879.html
