One of the DuckDB maintainers here. To clarify - the UI is not built into the DuckDB release. It is an extension that is downloaded and installed like any other extension. This extension happens to be developed by MotherDuck. We collaborated with them to streamline the experience - but fundamentally the extension is not distributed as part of DuckDB and works similarly to other extensions.
To be specific, the work we did was:
* Add the -ui command to the shell. This executes a SQL query (CALL start_ui()). The query that gets executed can be customized by the user through the .ui_command option - e.g. by setting .ui_command my_ui_function().
* The ui extension is automatically installed and loaded when the start_ui function is executed - similar to other trusted extensions we distribute. The automatic install and load can be disabled through configuration (SET autoinstall_known_extensions=false, SET autoload_known_extensions=false) and is also disabled when SET enable_external_access=false.
The nature of UI as an extension is somewhat hard to understand, since its installation method differs from other extensions. Even core ones. Some extensions autoload, some require INSTALL query, and this one has its own special builtin query. It at least feels more ingrained than other extensions by its user experience.
Then there's the (to me) entirely new feature of an extension providing a HTTP proxy for external web service. This part could have been more prominently explained.
Edit: the OP states that "built-in local UI for DuckDB" and "full-featured local web user interface is available out-of-the-box". These statements make me think this feature comes with the release binary, not that it's an extension.
To clarify my point: for me it's not the possible confusion of what this plugin does or how, but what this collaboration means for the future of DuckDB's no-cost and commercial usage.
I agree that the blog post seems to hint at the fact that this functionality is fully baked in in certain places - we've adjusted the blog post to be more explicit on the fact that this is an extension.
We have collaborated with MotherDuck on streamlining the experience of launching the UI through auto-installation, but the DuckDB Foundation still remains in full control of DuckDB and the extension ecosystem. This has no impact on that.
For further clarification:
* The auto-installation mechanism is identical to that of other trusted extensions - the auto-installation is triggered when a specific function is called that does not exist in the catalog - in this case the `start_ui` function. See [1]. The query I mentioned just calls that function. The only special feature here is the addition of the CLI flag (and what that flag executes is user-configurable).
* The HTTP server is necessary for the extension to function as the extension needs to communicate with the browser. The server is open-source as part of the extension code [2]. The server (1) fetches web resources (javascript/css) from ui.duckdb.org, and (2) communicates with localhost to co-ordinate the UI with DuckDB. Outside of these the server doesn't interface with other external web services.
I realized that the extension provides a HTTP API to DuckDB. Is this perhaps to become the official way to use DuckDB through HTTP? For me this is much more interesting than one particular UI.
To be specific, the work we did was:
* Add the -ui command to the shell. This executes a SQL query (CALL start_ui()). The query that gets executed can be customized by the user through the .ui_command option - e.g. by setting .ui_command my_ui_function().
* The ui extension is automatically installed and loaded when the start_ui function is executed - similar to other trusted extensions we distribute. The automatic install and load can be disabled through configuration (SET autoinstall_known_extensions=false, SET autoload_known_extensions=false) and is also disabled when SET enable_external_access=false.