# Performing common log-related tasks for Oracle DB instances
<a name="Appendix.Oracle.CommonDBATasks.Log"></a>

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
<a name="Appendix.Oracle.CommonDBATasks.SettingForceLogging"></a>

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
<a name="Appendix.Oracle.CommonDBATasks.AddingSupplementalLogging"></a>

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
<a name="Appendix.Oracle.CommonDBATasks.SwitchingLogfiles"></a>

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
<a name="Appendix.Oracle.CommonDBATasks.RedoLogs"></a>

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. <br />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
<a name="Appendix.Oracle.CommonDBATasks.DroppingRedoLogs"></a>

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
```