# Addressing


## Format

The canonical form of a PostgreSQL transport address is a schema-qualified quoted identifier:

```text
""table"".""schema""
```

Only the table name is mandatory. An address containing only a table name is a valid address, e.g. `MyTable`.

## Resolution

The address is resolved into a fully-qualified table name that includes the table name and its schema.

### Schema

The transport needs to determine which schema to use for a queue table when sending messages. The following API sets the schema for an endpoint when using [routing](/nservicebus/messaging/routing.md) to determine the destination queue for a message:

<!-- snippet: postgresql-multischema-config-for-endpoint -->

```cs
var routing = endpointConfiguration.UseTransport(new PostgreSqlTransport("connectionString"));

routing.RouteToEndpoint(typeof(MyMessage), "MyEndpoint");
routing.UseSchemaForEndpoint(endpointName: "MyEndpoint", schema: "my_schema");
```

<!-- endsnippet -->

There are several cases when routing is not used and the transport requires specific configuration to determine the schema for a queue table:

- [Error queue](/nservicebus/recoverability/configure-error-handling.md#configure-the-error-queue-address)
- [Audit queue](/nservicebus/operations/auditing.md#configuring-auditing)
- ServiceControl plugin queues
  - [Heartbeats plugin](/monitoring/heartbeats/install-plugin.md)
  - [Custom Checks plugin](/monitoring/custom-checks/install-plugin.md)
- [Overriding the default routing mechanism](/nservicebus/messaging/send-a-message.md#overriding-the-default-routing)

Use the following API to set the schema for a queue:

<!-- snippet: postgresql-multischema-config-for-queue -->

```cs
var transport = new PostgreSqlTransport("connectionString");

transport.Schema.UseSchemaForQueue(queueName: "myqueue", schema: "my_schema");
transport.Schema.UseSchemaForQueue(queueName: "myerror", schema: "sc");
```

<!-- endsnippet -->

The specified schema is used both when sending to a specific queue, and when a queue is set in endpoint configuration:

<!-- snippet: postgresql-multischema-config-for-queue-send -->

```cs
await messageSession.Send("myqueue", new MyMessage());
```

<!-- endsnippet -->

<!-- snippet: postgresql-multischema-config-for-queue-error -->

```cs
endpointConfiguration.SendFailedMessagesTo("myerror");
```

<!-- endsnippet -->

> [!NOTE]
> If the queue name contains a "." and the first part is not a schema name, enclose the queue name in double quotes.

<!-- snippet: postgresql-multischema-config-for-queue-heartbeats -->

```cs
endpointConfiguration.SendHeartbeatTo("\"Particular.ServiceControl\"");
```

<!-- endsnippet -->

The following values determine the schema, in priority order:

- A schema configured for a given queue via `UseSchemaForQueue`.
- A schema configured for a given endpoint via `UseSchemaForEndpoint`.
- A schema contained in the destination address.
- A default schema configured via `DefaultSchema`.
- Otherwise, `public` is used as a default schema.