datafusion-orc 0.10.0

Implementation of Apache ORC file format using Apache Arrow in-memory format
Documentation 
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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.

use crate::physical_exec::OrcOpener;
use datafusion::common::tree_node::TreeNodeRecursion;
use datafusion::common::DataFusionError;
use datafusion::datasource::physical_plan::{FileOpener, FileScanConfig, FileSource};
use datafusion::datasource::table_schema::TableSchema;
use datafusion::object_store::ObjectStore;
use datafusion::physical_plan::metrics::ExecutionPlanMetricsSet;
use datafusion::physical_plan::projection::ProjectionExprs;
use datafusion::physical_plan::PhysicalExpr;
use std::sync::Arc;

#[derive(Debug, Clone)]
pub struct OrcSource {
    metrics: ExecutionPlanMetricsSet,
    batch_size: usize,
    table_schema: TableSchema,
    projection: ProjectionExprs,
}

impl OrcSource {
    pub fn new(table_schema: TableSchema) -> Self {
        let table_schema_ref = table_schema.table_schema();
        let projection = ProjectionExprs::from_indices(
            &(0..table_schema_ref.fields().len()).collect::<Vec<_>>(),
            table_schema_ref,
        );
        Self {
            metrics: ExecutionPlanMetricsSet::default(),
            batch_size: 1024,
            table_schema,
            projection,
        }
    }
}

impl FileSource for OrcSource {
    fn create_file_opener(
        &self,
        object_store: Arc<dyn ObjectStore>,
        config: &FileScanConfig,
        _partition: usize,
    ) -> Result<Arc<dyn FileOpener>, DataFusionError> {
        OrcOpener::try_new(
            object_store,
            self.table_schema.table_schema().clone(),
            config.batch_size.unwrap_or(self.batch_size),
            self.projection.clone(),
        )
        .map(|f| Arc::new(f) as Arc<dyn FileOpener>)
    }

    fn table_schema(&self) -> &TableSchema {
        &self.table_schema
    }

    fn with_batch_size(&self, batch_size: usize) -> Arc<dyn FileSource> {
        Arc::new(Self {
            batch_size,
            ..self.clone()
        })
    }

    fn projection(&self) -> Option<&ProjectionExprs> {
        Some(&self.projection)
    }

    fn metrics(&self) -> &ExecutionPlanMetricsSet {
        &self.metrics
    }

    fn file_type(&self) -> &str {
        "orc"
    }

    fn try_pushdown_projection(
        &self,
        projection: &ProjectionExprs,
    ) -> Result<Option<Arc<dyn FileSource>>, DataFusionError> {
        let mut source = self.clone();
        source.projection = self.projection.try_merge(projection)?;
        Ok(Some(Arc::new(source)))
    }

    fn apply_expressions(
        &self,
        f: &mut dyn FnMut(&Arc<dyn PhysicalExpr>) -> Result<TreeNodeRecursion, DataFusionError>,
    ) -> Result<TreeNodeRecursion, DataFusionError> {
        datafusion::physical_plan::apply_expression_roots(self.projection.iter(), f)
    }
}