Description

The log_min_messages flag defines the minimum message severity level that is considered as an error statement. Messages for error statements are logged with the SQL statement. Valid values include debug5, debug4, debug3, debug2, debug1, info, notice, warning, error, log, fatal, and panic. Each severity level includes the subsequent levels mentioned above. For best practices, set the value to error. Changes should only be made in accordance with the organization’s logging policy.

Default value

By default log_min_error_statement is warning.

Rationale

Auditing helps in troubleshooting operational problems and also permits forensic analysis. If log_min_error_statement is not set to the correct value, messages may not be classified as error messages appropriately. An organization will need to decide their own threshold for logging log_min_messages flag.

Impact

Setting the threshold too low will might result in increased log storage size and length, making it difficult to find actual errors. Setting the threshold to warning logs most needed error messages. Setting the threshold to a higher severity level may result in some errors (that need troubleshooting) to not be logged.

Note: To effectively turn off logging failing statements, set this parameter to panic.

Note: Configuring the above flag does not require restarting the Cloud SQL instance.

Remediation

From the console

1. Go to the Cloud SQL Instances page in the Google Cloud console.
2. Select the PostgreSQL instance for which you want to enable the database flag.
3. Click Edit.
4. Scroll down to the Flags section.
5. Click Add item to set a flag that has not been set on the instance before. Choose the flag log_min_messages from the drop-down menu and set appropriate value.
6. Click Save.
7. Confirm your changes under the Flags section on the Overview page.

From the command line

1. Configure the log_min_messages database flag for every Cloud SQL PosgreSQL database instance using the below command.

gcloud sql instances patch <INSTANCE_NAME> --database-flags
log_min_messages=<DEBUG5|DEBUG4|DEBUG3|DEBUG2|DEBUG1|INFO|NOTICE|WARNING|ERROR|LOG|FATAL|PANIC>

Note: This command overwrites all database flags previously set. To keep flags previously set and add new ones, include the values for all flags you want set on the instance; any flag not specifically included is set to its default value. For flags that do not take a value, specify the flag name followed by an equals sign (=).

References

1. https://cloud.google.com/sql/docs/postgres/flags
2. https://www.postgresql.org/docs/9.6/runtime-config-logging.html#RUNTIME-CONFIG-LOGGING-WHEN