Document endpoint use for private networking needs.

README.md

@@ -167,6 +167,16 @@ For detailed streaming query guidance, see **[STREAMING.md](https://github.com/c
 
 For type support and examples, see **[TYPES.md](https://github.com/confluentinc/confluent-sql/blob/main/TYPES.md)**.
 
+
+## Private Networking Considerations
+
+By default, this driver uses the public Confluent Cloud API networking endpoint for the provided cloud provider and region. However, if the Flink database / Kafka cluster you intend to query requires private networking connectivity, then provide the appropriate Flink private networking base URL as the `endpoint` parameter
+to `connect()` or `Connection.__init__()`. Refer to the Confluent Cloud [Flink private networking documentation](https://docs.confluent.io/cloud/current/flink/concepts/flink-private-networking.html) for more information on composing your endpoint URL.
+
+Symptoms of using the public endpoint when private networking is required include:
+  * HTTP 429-related exceptions raised when submitting statements querying tables whose backing Kafka topics / clusters are configured for private networking only.
+  * Empty or surprisingly missing results when querying `INFORMATION_SCHEMA` or `SHOW TABLES`, due to silent filtering of private-networking-only tables/topics when querying the system catalog.
+
 ## Development
 
 ### Setup

src/confluent_sql/connection.py

@@ -64,11 +64,15 @@ def connect(  # noqa: PLR0913
             provided; must not be provided if endpoint is specified.
         database: The default Flink database (Kafka cluster) to use when resolving
             table/view/udf names (optional)
-        endpoint: The base URL for Confluent Cloud API (optional). If not provided, the endpoint
-            will be constructed based on the cloud_provider and cloud_region parameters in the
-            format "https://flink.{cloud_region}.{cloud_provider}.confluent.cloud". A trailing
-            slash is optional and will be stripped if provided (e.g., both
+        endpoint: The base URL for Confluent Cloud API (optional). If not provided, the public
+            networking endpoint will be constructed based on the cloud_provider and cloud_region
+            parameters in the format "https://flink.{cloud_region}.{cloud_provider}.confluent.cloud".
+            A trailing slash is optional and will be stripped if provided (e.g., both
             "https://custom.example.com" and "https://custom.example.com/" are accepted).
+
+            If your Kafka clusters / Flink tables require private networking, supply the base
+            endpoint URL here (`"https://flink.us-east-2.aws.private.confluent.cloud"` for example,
+            but cases and private networking technologies vary).
         dbname: Deprecated alias for database parameter (optional)
         result_page_fetch_pause_millis: Maximum milliseconds to wait between fetching pages of
             statement results (per statement). Defaults to 100ms. Prevents tight loops of requests
@@ -215,6 +219,10 @@ def __init__(  # noqa: PLR0913
                 endpoint will be constructed based on the cloud_provider and cloud_region
                 parameters in the format "https://flink.{cloud_region}.{cloud_provider}.confluent.cloud".
                 A trailing slash is optional and will be stripped if provided.
+
+                If your Kafka clusters / Flink tables require private networking, supply the base
+                endpoint URL here (`"https://flink.us-east-2.aws.private.confluent.cloud"` for
+                example, but cases and private networking technologies vary).
             database: The name of the database to use (optional)
             result_page_fetch_pause_millis: Milliseconds to possibly wait between fetching pages of
                 statement results. Defaults to 100ms. If most recent fetch of results for a