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Azure Database for PostgreSQL allows you to configure and access Postgres' standard logs. The logs can be used to identify, troubleshoot, and repair configuration errors and suboptimal performance. Logging information you can configure and access includes errors, query information, autovacuum records, connections, and checkpoints. (Access to transaction logs isn't available).
Audit logging is made available through a Postgres extension, pgaudit. To learn more, visit the auditing concepts article.
Configure logging
You can configure Postgres standard logging on your server using the logging server parameters. To learn more about Postgres log parameters, visit the When To Log and What To Log sections of the Postgres documentation. Most, but not all, Postgres logging parameters are available to configure in Azure Database for PostgreSQL.
To learn how to configure parameters in Azure Database for PostgreSQL, see the portal documentation or the CLI documentation.
Note
To configure a high volume of logs, you can add significant performance overhead. For example, statement logging can impact performance.
Access logs
Azure Database for PostgreSQL is integrated with Azure Monitor diagnostic settings. Diagnostic settings allow you to send PostgreSQL logs in JSON format to Azure Monitor Logs for analytics and alerting. You can also stream them to Event Hubs or archive them in Azure Storage.
Access control for logs
Access to server logs is controlled through Azure Role-Based Access Control (RBAC). Any role that provides read access to the server also allows downloading logs. This includes built-in roles such as:
- Reader
- Monitoring Reader
- Log Analytics Reader
- Or equivalent custom roles
Warning
Logs might contain sensitive information, such as credentials, depending on your logging configuration.
Data Retention Policy and Pricing
For logs sent to Event Hubs or a Storage account, you can set up a retention policy to automatically delete data after a certain period. Log Analytics costs depend on two factors:
- Data Ingestion: Charges are based on the volume of data that is ingested into the workspace.
- Data Retention: Logs stored in your Log Analytics workspace are kept free of charge for the first 31 days. Beyond this free retention period, there's a fee for storing data, calculated on a daily pro-rata basis, based on the amount of data (in GB) retained each month.
For a breakdown of the costs associated with data ingestion and retention, visit the Azure Monitor pricing page.
Log format
The following table describes the fields for the PostgreSQLLogs type. Depending on the output endpoint you choose, the fields included and the order in which they appear might vary.
| Field | Description |
|---|---|
| TenantId | Your tenant ID |
| SourceSystem | Azure |
| TimeGenerated [UTC] | Time stamp when the log was recorded in UTC |
| Type | Type of the log. Always AzureDiagnostics |
| SubscriptionId | GUID for the subscription that the server belongs to |
| ResourceGroup | Name of the resource group the server belongs to |
| ResourceProvider | Name of the resource provider. Always MICROSOFT.DBFORPOSTGRESQL |
| ResourceType | FlexibleServers |
| ResourceId | Resource URI |
| Resource | Name of the server |
| Category | PostgreSQLLogs |
| OperationName | LogEvent |
| errorLevel_s | Logging level, example: LOG, ERROR, NOTICE |
| processId_d | Process ID of the PostgreSQL backend |
| sqlerrcode_s | PostgreSQL Error code that follows the SQL standard's conventions for SQLSTATE codes |
| Message | Primary log message |
| Detail | Secondary log message (if applicable) |
| ColumnName | Name of the column (if applicable) |
| SchemaName | Name of the schema (if applicable) |
| DatatypeName | Name of the datatype (if applicable) |
| _ResourceId | Resource URI |
Known limitations
- Log Event Size: Query plans or log messages larger than 65 KB aren't captured in Azure Monitor Logs. This is a platform-wide Azure Monitor limit. As a result, complex queries (for example, those involving nested views) might generate incomplete or missing query plan output in server logs.
- Other Constraints: Other platform-wide limits apply to Azure Monitor Logs, such as alert rule quotas and query result size. For the complete list, refer to the Azure Monitor service limits documentation for details.