# Performing common log-related tasks for Oracle DB instances
Following, you can find how to perform certain common DBA tasks related to logging on your Amazon RDS DB instances running Oracle. To deliver a managed service experience, Amazon RDS doesn't provide shell access to DB instances, and restricts access to certain system procedures and tables that require advanced privileges.
For more information, see [Amazon RDS for Oracle database log files](USER_LogAccess.Concepts.Oracle.md).
**Topics**
+ [Setting force logging](#Appendix.Oracle.CommonDBATasks.SettingForceLogging)
+ [Setting supplemental logging](#Appendix.Oracle.CommonDBATasks.AddingSupplementalLogging)
+ [Switching online log files](#Appendix.Oracle.CommonDBATasks.SwitchingLogfiles)
+ [Adding online redo logs](#Appendix.Oracle.CommonDBATasks.RedoLogs)
+ [Dropping online redo logs](#Appendix.Oracle.CommonDBATasks.DroppingRedoLogs)
+ [Resizing online redo logs](Appendix.Oracle.CommonDBATasks.ResizingRedoLogs.md)
+ [Retaining archived redo logs](Appendix.Oracle.CommonDBATasks.RetainRedoLogs.md)
+ [Accessing online and archived redo logs](Appendix.Oracle.CommonDBATasks.Log.Download.md)
+ [Downloading archived redo logs from Amazon S3](Appendix.Oracle.CommonDBATasks.download-redo-logs.md)
## Setting force logging
In force logging mode, Oracle logs all changes to the database except changes in temporary tablespaces and temporary segments (`NOLOGGING` clauses are ignored). For more information, see [Specifying FORCE LOGGING mode](https://docs.oracle.com/cd/E11882_01/server.112/e25494/create.htm#ADMIN11096) in the Oracle documentation.
To set force logging, use the Amazon RDS procedure `rdsadmin.rdsadmin_util.force_logging`. The `force_logging` procedure has the following parameters.
****
| Parameter name | Data type | Default | Yes | Description |
| --- | --- | --- | --- | --- |
| `p_enable` | boolean | true | No | Set to `true` to put the database in force logging mode, `false` to remove the database from force logging mode. |
The following example puts the database in force logging mode.
```
EXEC rdsadmin.rdsadmin_util.force_logging(p_enable => true);
```
## Setting supplemental logging
If you enable supplemental logging, LogMiner has the necessary information to support chained rows and clustered tables. For more information, see [Supplemental logging](https://docs.oracle.com/cd/E11882_01/server.112/e22490/logminer.htm#SUTIL1582) in the Oracle documentation.
Oracle Database doesn't enable supplemental logging by default. To enable and disable supplemental logging, use the Amazon RDS procedure `rdsadmin.rdsadmin_util.alter_supplemental_logging`. For more information about how Amazon RDS manages the retention of archived redo logs for Oracle DB instances, see [Retaining archived redo logs](Appendix.Oracle.CommonDBATasks.RetainRedoLogs.md).
The `alter_supplemental_logging` procedure has the following parameters.
****
| Parameter name | Data type | Default | Required | Description |
| --- | --- | --- | --- | --- |
| `p_action` | varchar2 | — | Yes | `'ADD'` to add supplemental logging, `'DROP'` to drop supplemental logging. |
| `p_type` | varchar2 | null | No | The type of supplemental logging. Valid values are `'ALL'`, `'FOREIGN KEY'`, `'PRIMARY KEY'`, `'UNIQUE'`, or `PROCEDURAL`. |
The following example enables supplemental logging.
```
begin
rdsadmin.rdsadmin_util.alter_supplemental_logging(
p_action => 'ADD');
end;
/
```
The following example enables supplemental logging for all fixed-length maximum size columns.
```
begin
rdsadmin.rdsadmin_util.alter_supplemental_logging(
p_action => 'ADD',
p_type => 'ALL');
end;
/
```
The following example enables supplemental logging for primary key columns.
```
begin
rdsadmin.rdsadmin_util.alter_supplemental_logging(
p_action => 'ADD',
p_type => 'PRIMARY KEY');
end;
/
```
## Switching online log files
To switch log files, use the Amazon RDS procedure `rdsadmin.rdsadmin_util.switch_logfile`. The `switch_logfile` procedure has no parameters.
The following example switches log files.
```
EXEC rdsadmin.rdsadmin_util.switch_logfile;
```
## Adding online redo logs
An Amazon RDS DB instance running Oracle starts with four online redo logs, 128 MB each. To add additional redo logs, use the Amazon RDS procedure `rdsadmin.rdsadmin_util.add_logfile`.
The `add_logfile` procedure has the following parameters.
**Note**
The parameters are mutually exclusive.
****
| Parameter name | Data type | Default | Required | Description |
| --- | --- | --- | --- | --- |
| `bytes` | positive | null | No | The size of the log file in bytes. Use this parameter only if the size of the log is under 2147483648 bytes (2 GiB). Otherwise, RDS issues an error. For log sizes above this byte value, use the `p_size` parameter instead. |
| `p_size` | varchar2 | — | Yes | The size of the log file in kilobytes (K), megabytes (M), or gigabytes (G). |
The following command adds a 100 MB log file.
```
EXEC rdsadmin.rdsadmin_util.add_logfile(p_size => '100M');
```
## Dropping online redo logs
To drop redo logs, use the Amazon RDS procedure `rdsadmin.rdsadmin_util.drop_logfile`. The `drop_logfile` procedure has the following parameters.
****
| Parameter name | Data type | Default | Required | Description |
| --- | --- | --- | --- | --- |
| `grp` | positive | — | Yes | The group number of the log. |
The following example drops the log with group number 3.
```
EXEC rdsadmin.rdsadmin_util.drop_logfile(grp => 3);
```
You can only drop logs that have a status of unused or inactive. The following example gets the statuses of the logs.
```
SELECT GROUP#, STATUS FROM V$LOG;
GROUP# STATUS
---------- ----------------
1 CURRENT
2 INACTIVE
3 INACTIVE
4 UNUSED
```