yjshen commented on a change in pull request #811:
URL: https://github.com/apache/arrow-datafusion/pull/811#discussion_r692658418
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File path: datafusion/src/datasource/mod.rs
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@@ -36,3 +52,304 @@ pub(crate) enum Source<R = Box<dyn std::io::Read + Send +
Sync + 'static>> {
/// Read data from a reader
Reader(std::sync::Mutex<Option<R>>),
}
+
+#[derive(Debug, Clone)]
+/// A single file that should be read, along with its schema, statistics
+/// and partition column values that need to be appended to each row.
+pub struct PartitionedFile {
+ /// Path for the file (e.g. URL, filesystem path, etc)
+ pub file_path: String,
+ /// Schema of the file
+ pub schema: Schema,
+ /// Statistics of the file
+ pub statistics: Statistics,
+ // Values of partition columns to be appended to each row
+ // pub partition_value: Option<Vec<ScalarValue>>,
+ // Schema of partition columns
+ // pub partition_schema: Option<Schema>,
+ // We may include row group range here for a more fine-grained parallel
execution
+}
+
+impl From<String> for PartitionedFile {
+ fn from(file_path: String) -> Self {
+ Self {
+ file_path,
+ schema: Schema::empty(),
+ statistics: Default::default(),
+ }
+ }
+}
+
+impl std::fmt::Display for PartitionedFile {
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ write!(f, "{}", self.file_path)
+ }
+}
+
+#[derive(Debug, Clone)]
+/// A collection of files that should be read in a single task
+pub struct FilePartition {
+ /// The index of the partition among all partitions
+ pub index: usize,
+ /// The contained files of the partition
+ pub files: Vec<PartitionedFile>,
+}
+
+impl std::fmt::Display for FilePartition {
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ let files: Vec<String> = self.files.iter().map(|f|
f.to_string()).collect();
+ write!(f, "{}", files.join(", "))
+ }
+}
+
+#[derive(Debug, Clone)]
+/// All source files with same schema exists in a path
+pub struct SourceRootDescriptor {
+ /// All source files in the path
+ pub partition_files: Vec<PartitionedFile>,
+ /// The schema of the files
+ pub schema: SchemaRef,
+}
+
+/// Stream of
+pub type PartitionedFileStream =
+ Pin<Box<dyn Stream<Item = Result<PartitionedFile>> + Send + Sync +
'static>>;
+
+/// Builder for ['SourceRootDescriptor'] inside given path
+#[async_trait]
+pub trait SourceRootDescBuilder: Sync + Send + Debug {
+ /// Construct a ['SourceRootDescriptor'] from the provided path
+ fn get_source_desc(
+ path: &str,
+ object_store: Arc<dyn ObjectStore>,
+ ext: &str,
+ provided_schema: Option<Schema>,
+ collect_statistics: bool,
+ ) -> Result<SourceRootDescriptor> {
+ let mut results: Vec<Result<PartitionedFile>> = Vec::new();
+ futures::executor::block_on(async {
+ match Self::get_source_desc_async(
+ path,
+ object_store,
+ ext,
+ provided_schema,
+ collect_statistics,
+ )
+ .await
+ {
+ Ok(mut stream) => {
+ while let Some(pf) = stream.next().await {
+ results.push(pf);
+ }
+ }
+ Err(e) => {
+ results.push(Err(e));
+ }
+ }
+ });
+
+ let partition_results: Result<Vec<PartitionedFile>> =
+ results.into_iter().collect();
+ let partition_files = partition_results?;
+
+ // build a list of Parquet partitions with statistics and gather all
unique schemas
Review comment:
Yes, the `get_source_desc` is used to adapting `async` to `sync` to stop
propagating async to API.
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