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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
//! Data source traits
use std::any::Any;
use std::sync::Arc;
use async_trait::async_trait;
use datafusion_common::{DataFusionError, Statistics};
use datafusion_expr::{CreateExternalTable, LogicalPlan};
pub use datafusion_expr::{TableProviderFilterPushDown, TableType};
use crate::arrow::datatypes::SchemaRef;
use crate::error::Result;
use crate::execution::context::SessionState;
use crate::logical_expr::Expr;
use crate::physical_plan::ExecutionPlan;
/// Source table
#[async_trait]
pub trait TableProvider: Sync + Send {
/// Returns the table provider as [`Any`](std::any::Any) so that it can be
/// downcast to a specific implementation.
fn as_any(&self) -> &dyn Any;
/// Get a reference to the schema for this table
fn schema(&self) -> SchemaRef;
/// Get the type of this table for metadata/catalog purposes.
fn table_type(&self) -> TableType;
/// Get the create statement used to create this table, if available.
fn get_table_definition(&self) -> Option<&str> {
None
}
/// Get the Logical Plan of this table, if available.
fn get_logical_plan(&self) -> Option<&LogicalPlan> {
None
}
/// Create an ExecutionPlan that will scan the table.
/// The table provider will be usually responsible of grouping
/// the source data into partitions that can be efficiently
/// parallelized or distributed.
async fn scan(
&self,
state: &SessionState,
projection: Option<&Vec<usize>>,
filters: &[Expr],
// limit can be used to reduce the amount scanned
// from the datasource as a performance optimization.
// If set, it contains the amount of rows needed by the `LogicalPlan`,
// The datasource should return *at least* this number of rows if available.
limit: Option<usize>,
) -> Result<Arc<dyn ExecutionPlan>>;
/// Tests whether the table provider can make use of a filter expression
/// to optimise data retrieval.
#[deprecated(since = "20.0.0", note = "use supports_filters_pushdown instead")]
fn supports_filter_pushdown(
&self,
_filter: &Expr,
) -> Result<TableProviderFilterPushDown> {
Ok(TableProviderFilterPushDown::Unsupported)
}
/// Tests whether the table provider can make use of any or all filter expressions
/// to optimise data retrieval.
#[allow(deprecated)]
fn supports_filters_pushdown(
&self,
filters: &[&Expr],
) -> Result<Vec<TableProviderFilterPushDown>> {
filters
.iter()
.map(|f| self.supports_filter_pushdown(f))
.collect()
}
/// Get statistics for this table, if available
fn statistics(&self) -> Option<Statistics> {
None
}
/// Return an [`ExecutionPlan`] to insert data into this table, if
/// supported.
///
/// The returned plan should return a single row in a UInt64
/// column called "count" such as the following
///
/// ```text
/// +-------+,
/// | count |,
/// +-------+,
/// | 6 |,
/// +-------+,
/// ```
///
/// # See Also
///
/// See [`InsertExec`] for the common pattern of inserting a
/// single stream of `RecordBatch`es.
///
/// [`InsertExec`]: crate::physical_plan::insert::InsertExec
async fn insert_into(
&self,
_state: &SessionState,
_input: Arc<dyn ExecutionPlan>,
) -> Result<Arc<dyn ExecutionPlan>> {
let msg = "Insertion not implemented for this table".to_owned();
Err(DataFusionError::NotImplemented(msg))
}
}
/// A factory which creates [`TableProvider`]s at runtime given a URL.
///
/// For example, this can be used to create a table "on the fly"
/// from a directory of files only when that name is referenced.
#[async_trait]
pub trait TableProviderFactory: Sync + Send {
/// Create a TableProvider with the given url
async fn create(
&self,
state: &SessionState,
cmd: &CreateExternalTable,
) -> Result<Arc<dyn TableProvider>>;
}