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Solutions for common PostgreSQL connectivity, schema, and SSL issues in Data API builder.
Common questions
What is PostgreSQL support in DAB?
Data API builder supports PostgreSQL as a relational database back end. DAB connects using the Npgsql driver and translates REST and GraphQL requests into SQL queries. Both self-hosted PostgreSQL instances and managed services such as Azure Database for PostgreSQL are supported.
What connection string format does PostgreSQL use?
DAB uses an ADO.NET-style connection string for PostgreSQL. A typical string looks like Host=localhost;Port=5432;Database=mydb;Username=myuser;Password=mypassword;. Set the connection string in the data-source.connection-string field of dab-config.json or pass it via --connection-string in dab init.
Does DAB support PostgreSQL schemas?
Yes. DAB supports non-public schemas. Reference the schema explicitly in the entity's source field using the format schemaname.tablename (for example, sales.orders). The database user configured in the connection string must have USAGE privilege on the schema and SELECT, INSERT, UPDATE, or DELETE privileges on the target tables.
Common issues
Cannot connect to PostgreSQL container
Symptom: DAB fails to start with Failed to connect to localhost:5432 or a similar network error.
Cause: The PostgreSQL container port is not mapped or the container is not ready to accept connections.
Resolution: Confirm the container is running with docker ps and that port 5432 is mapped to the host. Use Host=localhost;Port=5432 in the connection string. If the container just started, allow a few seconds for PostgreSQL to initialize before starting DAB.
Password authentication failed
Symptom: DAB logs show 28P01: password authentication failed for user.
Cause: The username or password in the connection string is incorrect, or the PostgreSQL user is configured for a different authentication method such as peer or ident.
Resolution: Verify the credentials match those set when the PostgreSQL instance or container was created. For containers, check the POSTGRES_PASSWORD and POSTGRES_USER environment variables. If running locally, confirm pg_hba.conf allows md5 or scram-sha-256 authentication for the connecting host.
Schema not found when entity references a non-public schema
Symptom: DAB returns a relation "tablename" does not exist error even though the table exists in the database.
Cause: The entity's source field omits the schema prefix, so PostgreSQL searches only the public schema by default.
Resolution: Update the source value in dab-config.json to include the schema prefix, for example sales.orders. Confirm the database user has USAGE on the schema by running GRANT USAGE ON SCHEMA sales TO myuser; in psql.
SSL required error connecting to Azure Database for PostgreSQL
Symptom: Connections to Azure Database for PostgreSQL fail with SSL connection is required.
Cause: Azure Database for PostgreSQL enforces SSL by default. Connections without SSL are rejected.
Resolution: Append Ssl Mode=Require; to the connection string. For full certificate validation, also set Trust Server Certificate=false and provide the server CA certificate path via Root Certificate=path/to/ca.pem. Download the certificate bundle from the Azure portal under the server's Networking settings.
Stored procedures are not supported
Symptom: Configuring a PostgreSQL stored procedure or function as an entity source fails or the entity does not behave as expected.
Cause: Data API builder does not currently support stored procedures for PostgreSQL. This is a known limitation tracked in GitHub issue #1023.
Resolution: Use a table or view as the entity source instead. Follow the GitHub issue for updates on when PostgreSQL stored procedure support is added.
Database policy is not enforced for Create operations
Symptom: A create mutation or POST request succeeds even when a database policy should restrict the operation.
Cause: Database policy support for Create actions in PostgreSQL is not yet implemented. This is a known limitation tracked in GitHub issue #1334.
Resolution: Use role-based permissions to restrict create access until database policy support for PostgreSQL Create is available.
Database policy is not enforced for PUT and PATCH operations
Symptom: A PUT or PATCH request on a PostgreSQL entity succeeds even when a database policy should restrict it.
Cause: Database policy support for PUT and PATCH operations in PostgreSQL is not yet implemented. This is a known limitation tracked in GitHub issue #1372.
Resolution: Use role-based permissions to restrict update access until database policy support for PostgreSQL update operations is available.
On-Behalf-Of (OBO) authentication is not supported
Symptom: Configuring On-Behalf-Of (OBO) authentication for a PostgreSQL-backed DAB instance fails or the token is not forwarded to the database as expected.
Cause: OBO authentication is currently only supported for SQL Server and Azure SQL. Support for PostgreSQL, MySQL, and Azure Cosmos DB has not yet been implemented. This is a known limitation tracked in GitHub issue #3159.
Resolution: Use a supported authentication method such as connection string credentials or managed identity for PostgreSQL. Follow the GitHub issue for updates on when OBO support is expanded to non-SQL Server databases.