DBA日常管理之-查看日志
Posted 敏而好好学
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DBA日常管理工作有很多，检查磁盘空间状态，查看系统相关信息，检查监听是否正常，查看数据库实例是否能正常连接、访问，查看表空间是否有故障，查看日志文件是否正常，定时对数据库性能进行监控，分析AWR报告，整理警告日志、跟踪文件等，检查备份是否正常，校验备份文件是否有效，对索引进行统计分析等等。
今天，我们来学习一下其中一条，查看日志的切换频率及生成文件大小，通过观察相关信息可以调整online redo 的大小及切换频率。
在非归档模式主要是查询 v$log_history，归档模式主要是查询 v$archived_log，也可以查询 v$log_history 。
下面，我们来看看语句：
----非归档模式下日志切换频率
SELECT trunc(first_time) "Date",
to_char(first_time, 'Day') "Day",
count(1) "Total",
SUM(decode(to_char(first_time, 'hh24'),'00',1,0)) "h0",
SUM(decode(to_char(first_time, 'hh24'),'01',1,0)) "h1",
SUM(decode(to_char(first_time, 'hh24'),'02',1,0)) "h2",
SUM(decode(to_char(first_time, 'hh24'),'03',1,0)) "h3",
SUM(decode(to_char(first_time, 'hh24'),'04',1,0)) "h4",
SUM(decode(to_char(first_time, 'hh24'),'05',1,0)) "h5",
SUM(decode(to_char(first_time, 'hh24'),'06',1,0)) "h6",
SUM(decode(to_char(first_time, 'hh24'),'07',1,0)) "h7",
SUM(decode(to_char(first_time, 'hh24'),'08',1,0)) "h8",
SUM(decode(to_char(first_time, 'hh24'),'09',1,0)) "h9",
SUM(decode(to_char(first_time, 'hh24'),'10',1,0)) "h10",
SUM(decode(to_char(first_time, 'hh24'),'11',1,0)) "h11",
SUM(decode(to_char(first_time, 'hh24'),'12',1,0)) "h12",
SUM(decode(to_char(first_time, 'hh24'),'13',1,0)) "h13",
SUM(decode(to_char(first_time, 'hh24'),'14',1,0)) "h14",
SUM(decode(to_char(first_time, 'hh24'),'15',1,0)) "h15",
SUM(decode(to_char(first_time, 'hh24'),'16',1,0)) "h16",
SUM(decode(to_char(first_time, 'hh24'),'17',1,0)) "h17",
SUM(decode(to_char(first_time, 'hh24'),'18',1,0)) "h18",
SUM(decode(to_char(first_time, 'hh24'),'19',1,0)) "h19",
SUM(decode(to_char(first_time, 'hh24'),'20',1,0)) "h20",
SUM(decode(to_char(first_time, 'hh24'),'21',1,0)) "h21",
SUM(decode(to_char(first_time, 'hh24'),'22',1,0)) "h22",
SUM(decode(to_char(first_time, 'hh24'),'23',1,0)) "h23"
FROM v$log_history
group by trunc(first_time), to_char(first_time, 'Day')
Order by 1 desc
;
---归档模式下归档生成频率及大小
SELECT trunc(completion_time) "Time",
to_char(completion_time, 'Day') "Day",
dest_id,
creator,
applied,
status,
count(1) "Total",
round(sum(blocks*block_size)/1024/1024) "Total_mb",
round(SUM(decode(to_char(completion_time, 'hh24'),'00',blocks*block_size,0))/1024/1024) h0_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'01',blocks*block_size,0))/1024/1024) h1_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'02',blocks*block_size,0))/1024/1024) h2_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'03',blocks*block_size,0))/1024/1024) h3_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'04',blocks*block_size,0))/1024/1024) h4_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'05',blocks*block_size,0))/1024/1024) h5_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'06',blocks*block_size,0))/1024/1024) h6_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'07',blocks*block_size,0))/1024/1024) h7_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'08',blocks*block_size,0))/1024/1024) h8_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'09',blocks*block_size,0))/1024/1024) h9_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'10',blocks*block_size,0))/1024/1024) h10_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'11',blocks*block_size,0))/1024/1024) h11_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'12',blocks*block_size,0))/1024/1024) h12_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'13',blocks*block_size,0))/1024/1024) h13_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'14',blocks*block_size,0))/1024/1024) h14_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'15',blocks*block_size,0))/1024/1024) h15_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'16',blocks*block_size,0))/1024/1024) h16_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'17',blocks*block_size,0))/1024/1024) h17_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'18',blocks*block_size,0))/1024/1024) h18_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'19',blocks*block_size,0))/1024/1024) h19_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'20',blocks*block_size,0))/1024/1024) h20_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'21',blocks*block_size,0))/1024/1024) h21_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'22',blocks*block_size,0))/1024/1024) h22_mb,
round(SUM(decode(to_char(completion_time, 'hh24'),'23',blocks*block_size,0))/1024/1024) h23_mb
FROM v$archived_log
group by trunc(completion_time),
to_char(completion_time, 'Day'),
dest_id,
creator,
applied,
status
Order by 1 desc,3
;
下面，我们来对字段做个说明：
NAME：记录归档文件路径和名称。
THREAD#：归档线程号，RAC环境下适用。
SEQUENCE#：归档文件序号。
FIRST_TIME：等同于创建时间。
CREATOR：该条记录的创建者。
APPLIED：是否被应用，Data Guard环境下适用。
STATUS：该条记录的状态。
其中，CREATOR列标识该条记录的创建者，有下列几个值：
ARCH：表示由归档进程创建。
FGRD：表示由前台进程创建。
RMAN：表示由RMAN创建。
SRMN：表示由Standby端的RMAN创建。
LGWR：表示由Logwriter进程创建。
STATUS列标识该条记录的状态，有下列几个值：
A：指正常归档状态。
D：指该记录指向的归档文件已被删除。
U：指该记录指向的归档已不存用。
X：指该条记录失效，通常是当你在RMAN中执行了CROSSCHECK ARCHIVELOG后有可能出现。
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