# 调整联机重做日志的大小
<a name="Appendix.Oracle.CommonDBATasks.ResizingRedoLogs"></a>

运行 Oracle 的 Amazon RDS 数据库实例从四个联机重做日志 (每个日志的大小为 128 MB) 开始。以下示例说明如何使用 Amazon RDS 过程将每个日志的大小从 128 MB 调整到 512 MB。

```
/* Query V$LOG to see the logs.          */
/* You start with 4 logs of 128 MB each. */

SELECT GROUP#, BYTES, STATUS FROM V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
1          134217728  INACTIVE
2          134217728  CURRENT
3          134217728  INACTIVE
4          134217728  INACTIVE


/* Add four new logs that are each 512 MB */

EXEC rdsadmin.rdsadmin_util.add_logfile(bytes => 536870912);
EXEC rdsadmin.rdsadmin_util.add_logfile(bytes => 536870912);
EXEC rdsadmin.rdsadmin_util.add_logfile(bytes => 536870912);
EXEC rdsadmin.rdsadmin_util.add_logfile(bytes => 536870912);


/* Query V$LOG to see the logs. */ 
/* Now there are 8 logs.        */

SELECT GROUP#, BYTES, STATUS FROM V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
1          134217728  INACTIVE
2          134217728  CURRENT
3          134217728  INACTIVE
4          134217728  INACTIVE
5          536870912  UNUSED
6          536870912  UNUSED
7          536870912  UNUSED
8          536870912  UNUSED


/* Drop each inactive log using the group number. */

EXEC rdsadmin.rdsadmin_util.drop_logfile(grp => 1);
EXEC rdsadmin.rdsadmin_util.drop_logfile(grp => 3);
EXEC rdsadmin.rdsadmin_util.drop_logfile(grp => 4);


/* Query V$LOG to see the logs. */ 
/* Now there are 5 logs.        */

select GROUP#, BYTES, STATUS from V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
2          134217728  CURRENT
5          536870912  UNUSED
6          536870912  UNUSED
7          536870912  UNUSED
8          536870912  UNUSED


/* Switch logs so that group 2 is no longer current. */

EXEC rdsadmin.rdsadmin_util.switch_logfile;


/* Query V$LOG to see the logs.        */ 
/* Now one of the new logs is current. */

SQL>SELECT GROUP#, BYTES, STATUS FROM V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
2          134217728  ACTIVE
5          536870912  CURRENT
6          536870912  UNUSED
7          536870912  UNUSED
8          536870912  UNUSED


/* If the status of log 2 is still "ACTIVE", issue a checkpoint to clear it to "INACTIVE".  */

EXEC rdsadmin.rdsadmin_util.checkpoint;


/* Query V$LOG to see the logs.            */ 
/* Now the final original log is inactive. */

select GROUP#, BYTES, STATUS from V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
2          134217728  INACTIVE
5          536870912  CURRENT
6          536870912  UNUSED
7          536870912  UNUSED
8          536870912  UNUSED


# Drop the final inactive log.

EXEC rdsadmin.rdsadmin_util.drop_logfile(grp => 2);


/* Query V$LOG to see the logs.    */ 
/* Now there are four 512 MB logs. */

SELECT GROUP#, BYTES, STATUS FROM V$LOG;

GROUP#     BYTES      STATUS
---------- ---------- ----------------
5          536870912  CURRENT
6          536870912  UNUSED
7          536870912  UNUSED
8          536870912  UNUSED
```