Trait ContextProvider

pub trait ContextProvider {
    // Required methods
    fn get_table_source(
        &self,
        name: TableReference,
    ) -> Result<Arc<dyn TableSource>>;
    fn get_function_meta(&self, name: &str) -> Option<Arc<ScalarUDF>>;
    fn get_aggregate_meta(&self, name: &str) -> Option<Arc<AggregateUDF>>;
    fn get_window_meta(&self, name: &str) -> Option<Arc<WindowUDF>>;
    fn get_variable_type(&self, variable_names: &[String]) -> Option<DataType>;
    fn options(&self) -> &ConfigOptions;
    fn udf_names(&self) -> Vec<String>;
    fn udaf_names(&self) -> Vec<String>;
    fn udwf_names(&self) -> Vec<String>;

    // Provided methods
    fn get_file_type(&self, _ext: &str) -> Result<Arc<dyn FileType>> { ... }
    fn get_table_function_source(
        &self,
        _name: &str,
        _args: Vec<Expr>,
    ) -> Result<Arc<dyn TableSource>> { ... }
    fn create_cte_work_table(
        &self,
        _name: &str,
        _schema: SchemaRef,
    ) -> Result<Arc<dyn TableSource>> { ... }
    fn get_expr_planners(&self) -> &[Arc<dyn ExprPlanner>] { ... }
    fn get_type_planner(&self) -> Option<Arc<dyn TypePlanner>> { ... }
}

Provides the SQL query planner meta-data about tables and functions referenced in SQL statements, without a direct dependency on the datafusion Catalog structures such as TableProvider

Required Methods

fn get_table_source(&self, name: TableReference) -> Result<Arc<dyn TableSource>>

Returns a table by reference, if it exists

fn get_function_meta(&self, name: &str) -> Option<Arc<ScalarUDF>>

Return the scalar function with a given name, if any

fn get_aggregate_meta(&self, name: &str) -> Option<Arc<AggregateUDF>>

Return the aggregate function with a given name, if any

fn get_window_meta(&self, name: &str) -> Option<Arc<WindowUDF>>

Return the window function with a given name, if any

fn get_variable_type(&self, variable_names: &[String]) -> Option<DataType>

Return the system/user-defined variable type, if any

A user defined variable is typically accessed via @var_name

fn options(&self) -> &ConfigOptions

Return overall configuration options

fn udf_names(&self) -> Vec<String>

Return all scalar function names

fn udaf_names(&self) -> Vec<String>

Return all aggregate function names

fn udwf_names(&self) -> Vec<String>

Return all window function names

Provided Methods

fn get_file_type(&self, _ext: &str) -> Result<Arc<dyn FileType>>

Return the type of a file based on its extension (e.g. .parquet)

This is used to plan COPY statements

fn get_table_function_source( &self, _name: &str, _args: Vec<Expr>, ) -> Result<Arc<dyn TableSource>>

Getter for a table function

fn create_cte_work_table( &self, _name: &str, _schema: SchemaRef, ) -> Result<Arc<dyn TableSource>>

Provides an intermediate table that is used to store the results of a CTE during execution

CTE stands for “Common Table Expression”

Notes

We don’t directly implement this in SqlToRel as implementing this function often requires access to a table that contains execution-related types that can’t be a direct dependency of the sql crate (for example CteWorkTable).

The ContextProvider provides a way to “hide” this dependency.

fn get_expr_planners(&self) -> &[Arc<dyn ExprPlanner>]

Return ExprPlanner extensions for planning expressions

fn get_type_planner(&self) -> Option<Arc<dyn TypePlanner>>

Return TypePlanner extensions for planning data types

Implementors