alamb commented on code in PR #7334:
URL: https://github.com/apache/arrow-rs/pull/7334#discussion_r2018907063
##########
parquet/src/file/metadata/reader.rs:
##########
@@ -638,6 +676,53 @@ impl ParquetMetaDataReader {
}
}
+ #[cfg(all(feature = "async", feature = "arrow"))]
+ async fn load_metadata_via_suffix<F: MetadataSuffixFetch>(
+ &self,
+ fetch: &mut F,
+ prefetch: usize,
+ ) -> Result<(ParquetMetaData, Option<(usize, Bytes)>)> {
+ let suffix = fetch.fetch_suffix(prefetch.max(FOOTER_SIZE)).await?;
Review Comment:
It looks like `prefetch` is always the value of self.get_prefetch_size()
which already has at least FOOTER_SIZE bytes
Thus I think this line is unecessary.
I think it would be clearer if you removed the `prefetch` parameter, and
instead directly called `self.prefetch_size()` in the method
##########
parquet/src/file/metadata/reader.rs:
##########
@@ -638,6 +676,53 @@ impl ParquetMetaDataReader {
}
}
+ #[cfg(all(feature = "async", feature = "arrow"))]
+ async fn load_metadata_via_suffix<F: MetadataSuffixFetch>(
+ &self,
+ fetch: &mut F,
+ prefetch: usize,
+ ) -> Result<(ParquetMetaData, Option<(usize, Bytes)>)> {
+ let suffix = fetch.fetch_suffix(prefetch.max(FOOTER_SIZE)).await?;
+ let suffix_len = suffix.len();
Review Comment:
The code from here on down seems like it is copy/pasted from `load_metadata`
-- could you please try and avoid duplication if possible by refactoring the
common code into a shared method?
##########
parquet/src/arrow/async_reader/store.rs:
##########
@@ -45,29 +46,35 @@ use tokio::runtime::Handle;
/// println!("Found Blob with {}B at {}", meta.size, meta.location);
///
/// // Show Parquet metadata
-/// let reader = ParquetObjectReader::new(storage_container, meta);
+/// let reader = ParquetObjectReader::new(storage_container, meta.location,
Some(meta.size));
/// 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,
+ path: Path,
+ file_size: Option<usize>,
metadata_size_hint: Option<usize>,
preload_column_index: bool,
preload_offset_index: bool,
runtime: Option<Handle>,
}
impl ParquetObjectReader {
- /// Creates a new [`ParquetObjectReader`] for the provided [`ObjectStore`]
and [`ObjectMeta`]
+ /// Creates a new [`ParquetObjectReader`] for the provided [`ObjectStore`]
and [`Path`].
///
- /// [`ObjectMeta`] can be obtained using [`ObjectStore::list`] or
[`ObjectStore::head`]
- pub fn new(store: Arc<dyn ObjectStore>, meta: ObjectMeta) -> Self {
+ /// The file size is optional, and if provided, it will ensure that only
bounded range requests
+ /// are used. If file size is not provided, the reader will use suffix
range requests to fetch
+ /// the metadata.
+ ///
+ /// The file size can be obtained using [`ObjectStore::list`] or
[`ObjectStore::head`].
+ pub fn new(store: Arc<dyn ObjectStore>, path: Path, file_size:
Option<usize>) -> Self {
Review Comment:
What do you think about not including the optional`file_size` in the
constructor, and instead add a `with_file_size` method? I think that might be
more consistent with the `metadata_size_hint` and the other options on this
struct.
```suggestion
pub fn new(store: Arc<dyn ObjectStore>, path: Path) -> Self {
```
And then you would make one of these things like
```rust
let reader = ParquetObjectReader::new(store, meta.location)
.with_size(Some(meta.size))
.with_runtime(rt.handle().clone());
```
I think as long as we left documentation that clearly stated that providing
the size up front was an important optimization to avoid extra calls, this
would be ok
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