It looks like you're encountering an issue with the database connection in Airbyte, specifically with the HikariDataSource. This error is commonly seen in various deployment scenarios and can be due to several reasons. Here are some steps you can take to troubleshoot and resolve this issue: 1. Database Initialization: Ensure that your database is fully initialized and ready to accept connections. Sometimes, the database might still be starting up when Airbyte tries to connect. You can see similar logs in the [forum post](https://discuss.airbyte.io/t/1264) where the database was not ready yet:

2022-06-01 05:12:49 INFO i.a.d.Database(createWithRetryTimeout):71 - Database is not ready yet. Please wait a moment, it might still be initializing...

2. Database Configuration: Verify that your database configuration is correct. This includes checking the database URL, username, password, and any other connection parameters. Incorrect configurations can lead to connection failures. 3. Network Issues: Ensure that there are no network issues preventing Airbyte from reaching the database. This is especially important if your database is hosted externally or in a different network segment. For example, in the [AWS EKS deployment issue](https://discuss.airbyte.io/t/2129), network configuration was a potential cause:

Airbyte-db pod status is Error and error is “error getting connection from data source hikaridatasource (hikaripool-1)”

4. Database Availability Check: Airbyte performs a database availability check before establishing a connection. If this check fails, it could indicate that the database is not reachable or there are issues with the database service itself. You can see a similar error in the [GitHub issue](https://github.com/airbytehq/airbyte/issues/31021):

2023-10-03 15:24:18 ERROR i.a.d.c.DatabaseAvailabilityCheck(lambda$isDatabaseConnected$1):78 - Failed to verify database connection.

5. Logs and Error Messages: Review the logs and error messages carefully. They can provide insights into what might be going wrong. For instance, in the [Helm Chart deployment issue](https://github.com/airbytehq/airbyte/issues/17841), the error logs indicated a problem with the HikariDataSource:

2022-10-11 13:32:38 ERROR i.a.c.p.ConfigRepository(healthCheck):109 - Health check error:     org.jooq.exception.DataAccessException: Error getting connection from data source HikariDataSource (HikariPool-1)

By following these steps, you should be able to identify and resolve the issue with the database connection in Airbyte. If the problem persists, you may want to check the Airbyte documentation or seek further assistance from the Airbyte community. For more detailed troubleshooting, you can refer to the relevant discussions and issues: - [Failed to connect to external postgres DB](https://discuss.airbyte.io/t/1264) - [AWS EKS deployment issue](https://discuss.airbyte.io/t/2129) - [Helm Chart deployment issue](https://github.com/airbytehq/airbyte/issues/17841) - [Database connection issue](https://github.com/airbytehq/airbyte/issues/31021)

The error

org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for azure replication users

indicates that the PostgreSQL server has reached its maximum number of allowed connections, and the remaining connection slots are reserved for Azure replication users. This is a common issue when the number of active connections to the database exceeds the configured limit. ### Possible Causes 1. Connection Limit Reached: The PostgreSQL server has a limit on the number of concurrent connections it can handle. When this limit is reached, new connection attempts are rejected with the error you are seeing. 2. Reserved Slots for Replication: Azure PostgreSQL reserves a certain number of connection slots specifically for replication purposes. When the general connection limit is reached, only these reserved slots remain, which are not available for regular connections. ### Steps to Resolve 1. Increase the Connection Limit: You can increase the maximum number of allowed connections in your PostgreSQL configuration. This can be done by modifying the

max_connections

parameter in the PostgreSQL configuration file (

postgresql.conf

) or through the Azure portal if you are using Azure Database for PostgreSQL. 2. Optimize Connection Usage: Ensure that your application is efficiently managing database connections. Use connection pooling to reuse existing connections rather than opening new ones for each request. Libraries like HikariCP can help manage connection pools effectively. 3. Monitor and Close Idle Connections: Regularly monitor your database for idle connections and close them if they are no longer needed. This can help free up connection slots for new requests. 4. Review Application Code: Check your application code to ensure that connections are being properly closed after use. Leaking connections can quickly exhaust the available connection slots. ### Example Configuration Change If you have access to the PostgreSQL configuration file, you can increase the

max_connections

parameter as follows:

sql # postgresql.conf max_connections = 200  # Increase this value as needed

After making this change, restart the PostgreSQL server to apply the new configuration. ### Additional Resources For more information on managing connections in Azure Database for PostgreSQL, you can refer to the official documentation: - [Azure Database for PostgreSQL - Connection Limits](https://learn.microsoft.com/en-us/azure/postgresql/concepts-limits) By following these steps, you should be able to resolve the connection slot issue and ensure that your application can connect to the PostgreSQL database without encountering this error.