Oracle Alert Log and PostgreSQL Error Log

Feature compatibility	AWS SCT / AWS DMS automation level	AWS SCT action code index	Key differences
	N/A	N/A	Use Event Notifications Subscription with Amazon Simple Notification Service.

Oracle Usage

The primary Oracle error log file is the Alert Log. It contains verbose information about database activity including informational messages and errors. Each event includes a timestamp indicating when the event occurred. The Alert Log filename format is alert<sid>.log.

The Alert Log is the first place to look when troubleshooting or investigating errors, failures, and other messages indicating a potential database problem. Common events logged in the Alert Log include:

• Database startup or shutdown.

• Database redo log switch.

• Database errors and warnings, which begin with ORA- followed by an Oracle error number.

• Network and connection issues.

• Links for a detailed trace files about specific database events.

The Oracle Alert Log can be found inside the database Automatic Diagnostics Repository (ADR), which is a hierarchical file-based repository for diagnostic information: $ADR_BASE/diag/rdbms/{DB-name}/{SID}/trace.

In addition, several other Oracle server components have unique log files such as the database listener and the Automatic Storage Manager (ASM).

Examples

The following screenshot displays partial contents of the Oracle database Alert Log File.

For more information, see Monitoring Errors and Alerts in the Oracle documentation.

PostgreSQL Usage

PostgreSQL provides detailed logging and reporting of errors that occur during the database and connected sessions lifecycle. In an Amazon Aurora deployment, these informational and error messages are accessible using the Amazon RDS console.

PostgreSQL and Oracle Error Codes

Oracle	PostgreSQL
ORA-00001: unique constraint (string.string) violated	SQLSTATE[23505]: Unique violation: 7 ERROR: duplicate key value violates unique constraint "constraint_name"

For more information, see PostgreSQL Error Codes in the PostgreSQL documentation.

PostgreSQL Error Log Types

Log type	Information written to log
DEBUG1…DEBUG5	Provides successively-more-detailed information for use by developers
INFO	Provides information implicitly requested by the user
NOTICE	Provides information that might be helpful to users
WARNING	Provides warnings of likely problems
ERROR	Reports an error that caused the current command to abort
LOG	Reports information of interest to administrators
FATAL	Reports an error that caused the current session to abort
PANIC	Reports an error that caused all database sessions to abort

For more information, see Error Reporting and Logging in the PostgreSQL documentation.

Examples

Access the PostgreSQL error log using the Amazon RDS or Aurora management console.

1. Sign in to your AWS console and choose RDS.

2. Choose Databases and select your database.

3. Choose Logs & events.

   

4. Scroll down to the Logs section and select the log to inspect. For example, select the log during the hour the data was experiencing problems. The following screen shot displays partial contents of a PostgreSQL database error log as viewed from the Amazon RDS Management Console.

   

5. Choose one of the logs.

   

PostgreSQL Error Log Configuration

The following tables shows parameters that control how and where PostgreSQL log and errors files will be placed.

Parameter	Description
log_filename	Sets the file name pattern for log files. Modifiable by an Aurora Database Parameter Group.
log_rotation_age	(min) Automatic log file rotation will occur after N minutes. Modifiable by an Aurora Database Parameter Group.
log_rotation_size	(kB) Automatic log file rotation will occur after N kilobytes. Modifiable by an Aurora Database Parameter Group.
log_min_messages	Sets the message levels that are logged (DEBUG, ERROR, INFO, and so on). Modifiable by an Aurora Database Parameter Group
log_min_error_statement	Causes all statements generating error at or above this level to be logged (DEBUG, ERROR, INFO, and so on). Modifiable by an Aurora Database Parameter Group.
log_min_duration_statement	Sets the minimum run time above which statements will be logged (ms). Modifiable by an Aurora Database Parameter Group

Modifications to certain parameters, such as log_directory (which sets the destination directory for log files) or logging_collector (which start a subprocess to capture stderr output and/or csvlogs into log files) are disabled for Aurora PostgreSQL instances.