datafusion-orc 0.10.0

// 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 std::collections::HashMap;
use std::fmt::Debug;
use std::sync::Arc;

use datafusion::arrow::datatypes::{Schema, SchemaRef};
use datafusion::common::Statistics;
use datafusion::datasource::file_format::file_compression_type::FileCompressionType;
use datafusion::datasource::file_format::FileFormat;
use datafusion::datasource::physical_plan::{FileScanConfig, FileSource};
use datafusion::datasource::table_schema::TableSchema;
use datafusion::error::{DataFusionError, Result};
use datafusion::object_store::path::Path;
use datafusion::object_store::{ObjectMeta, ObjectStore};
use datafusion::physical_plan::ExecutionPlan;
use futures::TryStreamExt;
use orc_rust::reader::metadata::read_metadata_async;

use crate::OrcSource;
use async_trait::async_trait;
use datafusion::catalog::Session;
use datafusion::datasource::source::DataSourceExec;
use futures_util::StreamExt;

use super::object_store_reader::ObjectStoreReader;

async fn fetch_schema(store: &Arc<dyn ObjectStore>, file: &ObjectMeta) -> Result<(Path, Schema)> {
    let loc_path = file.location.clone();
    let mut reader = ObjectStoreReader::new(Arc::clone(store), file.clone());
    let metadata = read_metadata_async(&mut reader)
        .await
        .map_err(|e| DataFusionError::External(Box::new(e)))?;
    let schema = metadata
        .root_data_type()
        .create_arrow_schema(&HashMap::default());
    Ok((loc_path, schema))
}

#[derive(Clone, Debug)]
pub struct OrcFormat;

#[async_trait]
impl FileFormat for OrcFormat {
    fn get_ext(&self) -> String {
        "orc".to_string()
    }

    fn get_ext_with_compression(&self, _compression: &FileCompressionType) -> Result<String> {
        Ok("orc".to_string())
    }

    fn compression_type(&self) -> Option<FileCompressionType> {
        None
    }

    async fn infer_schema(
        &self,
        state: &dyn Session,
        store: &Arc<dyn ObjectStore>,
        objects: &[ObjectMeta],
    ) -> Result<SchemaRef> {
        let mut schemas: Vec<_> = futures::stream::iter(objects)
            .map(|object| fetch_schema(store, object))
            .boxed() // Workaround https://github.com/rust-lang/rust/issues/64552
            .buffered(
                state
                    .config_options()
                    .execution
                    .meta_fetch_concurrency
                    .into(),
            )
            .try_collect()
            .await?;

        // Schema inference adds fields based the order they are seen
        // which depends on the order the files are processed. For some
        // object stores (like local file systems) the order returned from list
        // is not deterministic. Thus, to ensure deterministic schema inference
        // sort the files first.
        // https://github.com/apache/datafusion/pull/6629
        schemas.sort_by(|(location1, _), (location2, _)| location1.cmp(location2));

        let schemas = schemas
            .into_iter()
            .map(|(_, schema)| schema)
            .collect::<Vec<_>>();

        let schema = Schema::try_merge(schemas)?;

        Ok(Arc::new(schema))
    }

    async fn infer_stats(
        &self,
        _state: &dyn Session,
        _store: &Arc<dyn ObjectStore>,
        table_schema: SchemaRef,
        _object: &ObjectMeta,
    ) -> Result<Statistics> {
        Ok(Statistics::new_unknown(&table_schema))
    }

    async fn create_physical_plan(
        &self,
        _state: &dyn Session,
        conf: FileScanConfig,
    ) -> Result<Arc<dyn ExecutionPlan>> {
        Ok(DataSourceExec::from_data_source(conf))
    }

    fn file_source(&self, table_schema: TableSchema) -> Arc<dyn FileSource> {
        Arc::new(OrcSource::new(table_schema))
    }
}