Trait datafusion_expr::TableSource

source ·

pub trait TableSource: Sync + Send {
    // Required methods
    fn as_any(&self) -> &dyn Any;
    fn schema(&self) -> SchemaRef;

    // Provided methods
    fn constraints(&self) -> Option<&Constraints> { ... }
    fn table_type(&self) -> TableType { ... }
    fn supports_filter_pushdown(
        &self,
        _filter: &Expr,
    ) -> Result<TableProviderFilterPushDown> { ... }
    fn supports_filters_pushdown(
        &self,
        filters: &[&Expr],
    ) -> Result<Vec<TableProviderFilterPushDown>> { ... }
    fn get_logical_plan(&self) -> Option<&LogicalPlan> { ... }
    fn get_column_default(&self, _column: &str) -> Option<&Expr> { ... }
}

Expand description

Access schema information and filter push-down capabilities.

The TableSource trait is used during logical query planning and optimizations and provides a subset of the functionality of the TableProvider trait in the (core) datafusion crate. The TableProvider trait provides additional capabilities needed for physical query execution (such as the ability to perform a scan).

The reason for having two separate traits is to avoid having the logical plan code be dependent on the DataFusion execution engine. Some projects use DataFusion’s logical plans and have their own execution engine.