Oracle 参数 LOG_ARCHIVE_FORMAT 官方解释，作用，如何配置最优化建议
本站中文解释
的参数
LOG_ARCHIVE_FORMAT是oracle的参数，用来设置归档日志的归档文件的文件名格式。
LOG_ARCHIVE_FORMAT参数的正确设置：
1、定义LOG_ARCHIVE_FORMAT参数
可以在参数文件中使用LOG_ARCHIVE_FORMAT参数来定义归档文件名格式，格式形如：
log_archive_format = ‘&UNDO .arc’
其中“&”是必须的，用来包含日志文件名中几个常用符号，“UNDO”表示日志文件名格式中来自undo主段的日志文件，”.arc”表示后缀。
2、创建日志文件
Oracle创建日志文件时，会根据LOG_ARCHIVE_FORMAT参数定义的文件名格式生成归档文件的文件名。如果设置了参数log_archive_dest_X，日志文件会写入到指定的位置。
例如：
ALTER SYSTEM SET LOG_ARCHIVE_FORMAT=‘&UNDO.arc’ SCOPE=spfile;
ALTER SYSTEM SET log_archive_dest_1=’LOCATION=c:\oracle\archive’ SCOPE=spfile;
官方英文解释
Use LOG_ARCHIVE_FORMAT to specify the default filename format when archiving redo log files.
| Property | Description |
|---|---|
|
Parameter type |
String |
|
Syntax |
|
|
Default value |
Operating system-dependent |
|
Modifiable |
No |
|
Modifiable in a PDB |
No |
|
Range of values |
Any string that resolves to a valid filename |
|
Basic |
No |
|
Oracle RAC |
Multiple instances can have different values, but identical values are recommended. |
LOG_ARCHIVE_FORMAT is applicable only if you are using the redo log in ARCHIVELOG mode. Use a text string and variables to specify the default filename format when archiving redo log files. The string generated from this format is appended to the string specified in the LOG_ARCHIVE_DEST parameter.
The following variables can be used in the format:
%s log sequence number
%S log sequence number, zero filled
%t thread number
%T thread number, zero filled
%a activation ID
%d database ID
%r resetlogs ID that ensures unique names are constructed for the archived log files across multiple incarnations of the database
Using uppercase letters for the variables (for example, %S) causes the value to be fixed length and padded to the left with zeros. An example of specifying the archive redo log filename format follows:
LOG_ARCHIVE_FORMAT = 'log%t_%s_%r.arc'
Archive log file names must contain each of the elements %s (sequence), %t (thread), and %r (resetlogs ID) to ensure that all archive log file names are unique. If the LOG_ARCHIVE_FORMAT initialization parameter is set in the parameter file, then make sure the parameter value contains the %s, %t, and %r elements. Otherwise, the following error is displayed at the time of instance startup:
ORA-19905: log_archive_format must contain %s, %t and %r
Neither LOG_ARCHIVE_DEST nor LOG_ARCHIVE_FORMAT have to be complete file or directory specifiers themselves; they only need to form a valid file path after the variables are substituted into LOG_ARCHIVE_FORMAT and the two parameters are concatenated together.
LOG_ARCHIVE_FORMAT is ignored in these cases:
-
For archived log files that go to the fast recovery area
-
When
LOG_ARCHIVE_DEST[_n]points to the root of an Oracle ASM disk group (for example,+DATA). The directory of a disk group (for example, +DATA/logs) must be specified for the parameter to be honored.
In these cases where LOG_ARCHIVE_FORMAT is ignored, an Oracle ASM file name is used. See Oracle Automatic Storage
Management Administrator’s Guide for more information on Oracle ASM file names.
See Also:
-
Oracle Database Backup and
Recovery User’s Guide, Oracle Data Guard Concepts
and Administration, and Oracle Real Application
Clusters Administration and Deployment Guide for more information about this parameter -
Your operating system- specific Oracle documentation for the default value and range of values for
LOG_ARCHIVE_FORMAT
