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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 std::ops::Range;
use std::sync::Arc;
use bytes::Bytes;
use futures::future::BoxFuture;
use futures::{FutureExt, TryFutureExt};
use object_store::{ObjectMeta, ObjectStore};
use crate::arrow::async_reader::{AsyncFileReader, MetadataLoader};
use crate::errors::Result;
use crate::file::metadata::ParquetMetaData;
/// Reads Parquet files in object storage using [`ObjectStore`].
///
/// ```no_run
/// # use std::io::stdout;
/// # use std::sync::Arc;
/// # use object_store::azure::MicrosoftAzureBuilder;
/// # use object_store::ObjectStore;
/// # use object_store::path::Path;
/// # use parquet::arrow::async_reader::ParquetObjectReader;
/// # use parquet::arrow::ParquetRecordBatchStreamBuilder;
/// # use parquet::schema::printer::print_parquet_metadata;
/// # async fn run() {
/// // Populate configuration from environment
/// let storage_container = Arc::new(MicrosoftAzureBuilder::from_env().build().unwrap());
/// let location = Path::from("path/to/blob.parquet");
/// let meta = storage_container.head(&location).await.unwrap();
/// println!("Found Blob with {}B at {}", meta.size, meta.location);
///
/// // Show Parquet metadata
/// let reader = ParquetObjectReader::new(storage_container, meta);
/// let builder = ParquetRecordBatchStreamBuilder::new(reader).await.unwrap();
/// print_parquet_metadata(&mut stdout(), builder.metadata());
/// # }
/// ```
#[derive(Clone, Debug)]
pub struct ParquetObjectReader {
store: Arc<dyn ObjectStore>,
meta: ObjectMeta,
metadata_size_hint: Option<usize>,
preload_column_index: bool,
preload_offset_index: bool,
}
impl ParquetObjectReader {
/// Creates a new [`ParquetObjectReader`] for the provided [`ObjectStore`] and [`ObjectMeta`]
///
/// [`ObjectMeta`] can be obtained using [`ObjectStore::list`] or [`ObjectStore::head`]
pub fn new(store: Arc<dyn ObjectStore>, meta: ObjectMeta) -> Self {
Self {
store,
meta,
metadata_size_hint: None,
preload_column_index: false,
preload_offset_index: false,
}
}
/// Provide a hint as to the size of the parquet file's footer,
/// see [fetch_parquet_metadata](crate::arrow::async_reader::fetch_parquet_metadata)
pub fn with_footer_size_hint(self, hint: usize) -> Self {
Self {
metadata_size_hint: Some(hint),
..self
}
}
/// Load the Column Index as part of [`Self::get_metadata`]
pub fn with_preload_column_index(self, preload_column_index: bool) -> Self {
Self {
preload_column_index,
..self
}
}
/// Load the Offset Index as part of [`Self::get_metadata`]
pub fn with_preload_offset_index(self, preload_offset_index: bool) -> Self {
Self {
preload_offset_index,
..self
}
}
}
impl AsyncFileReader for ParquetObjectReader {
fn get_bytes(&mut self, range: Range<usize>) -> BoxFuture<'_, Result<Bytes>> {
self.store
.get_range(&self.meta.location, range)
.map_err(|e| e.into())
.boxed()
}
fn get_byte_ranges(&mut self, ranges: Vec<Range<usize>>) -> BoxFuture<'_, Result<Vec<Bytes>>>
where
Self: Send,
{
async move {
self.store
.get_ranges(&self.meta.location, &ranges)
.await
.map_err(|e| e.into())
}
.boxed()
}
fn get_metadata(&mut self) -> BoxFuture<'_, Result<Arc<ParquetMetaData>>> {
Box::pin(async move {
let preload_column_index = self.preload_column_index;
let preload_offset_index = self.preload_offset_index;
let file_size = self.meta.size;
let prefetch = self.metadata_size_hint;
let mut loader = MetadataLoader::load(self, file_size, prefetch).await?;
loader
.load_page_index(preload_column_index, preload_offset_index)
.await?;
Ok(Arc::new(loader.finish()))
})
}
}
#[cfg(test)]
mod tests {
use std::sync::Arc;
use futures::TryStreamExt;
use arrow::util::test_util::parquet_test_data;
use object_store::local::LocalFileSystem;
use object_store::path::Path;
use object_store::ObjectStore;
use crate::arrow::async_reader::ParquetObjectReader;
use crate::arrow::ParquetRecordBatchStreamBuilder;
#[tokio::test]
async fn test_simple() {
let res = parquet_test_data();
let store = LocalFileSystem::new_with_prefix(res).unwrap();
let mut meta = store
.head(&Path::from("alltypes_plain.parquet"))
.await
.unwrap();
let store = Arc::new(store) as Arc<dyn ObjectStore>;
let object_reader = ParquetObjectReader::new(Arc::clone(&store), meta.clone());
let builder = ParquetRecordBatchStreamBuilder::new(object_reader)
.await
.unwrap();
let batches: Vec<_> = builder.build().unwrap().try_collect().await.unwrap();
assert_eq!(batches.len(), 1);
assert_eq!(batches[0].num_rows(), 8);
meta.location = Path::from("I don't exist.parquet");
let object_reader = ParquetObjectReader::new(store, meta);
// Cannot use unwrap_err as ParquetRecordBatchStreamBuilder: !Debug
match ParquetRecordBatchStreamBuilder::new(object_reader).await {
Ok(_) => panic!("expected failure"),
Err(e) => {
let err = e.to_string();
assert!(
err.contains("not found: No such file or directory (os error 2)"),
"{}",
err
);
}
}
}
}