timsaucer opened a new issue, #1571: URL: https://github.com/apache/datafusion-python/issues/1571
## Background DataFusion's `SessionContext` exposes `register_variable(var_type, provider)` and `deregister_variable(var_type)` for plugging in a `VarProvider` that resolves SQL ``@var`` / ``@@var`` references at execution time. These were surfaced during a v54 upstream coverage audit but are not exposed in the Python bindings. ## Upstream signature ```rust pub fn register_variable(&self, var_type: VarType, provider: Arc<dyn VarProvider + Send + Sync>) pub fn deregister_variable(&self, var_type: VarType) -> Option<Arc<dyn VarProvider + Send + Sync>> ``` `VarProvider` is a small trait with `get_value(&self, name: Vec<String>) -> Result<ScalarValue>` and `get_type(&self, name: &[String]) -> Option<DataType>`. ## User value Enables SQL like ``SELECT * FROM sales WHERE region = @current_region AND user_id = @user_id`` where the provider supplies per-query values. Useful for multi-tenant SaaS embedders, BI / notebook tools that want session-scoped parameters without f-string interpolation (no SQL injection risk), and tools porting MySQL / Postgres SQL that uses session variables. ## Why deferred Effort estimate is medium (~250-400 LOC): needs a `PyVarProvider` Rust wrapper that calls back into a user-supplied Python object across the GIL boundary, plus the register / deregister bindings on `PySessionContext`, plus a Python-facing ABC. No open user requests at the time of audit, so the work is currently speculative. Filed for tracking; revisit when a concrete user need surfaces or to complete the upstream surface area. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
