[GitHub] [arrow-datafusion] Jefffrey commented on a diff in pull request #5860: when inferring the schema of compressed CSV, decompress before newline-delimited chunking

["Jefffrey (via GitHub)" <gi...@apache.org>]

Jefffrey commented on code in PR #5860:
URL: https://github.com/apache/arrow-datafusion/pull/5860#discussion_r1160340764


##########
datafusion/core/src/datasource/file_format/csv.rs:
##########
@@ -124,8 +154,13 @@ impl FileFormat for CsvFormat {
         let mut records_to_read = self.schema_infer_max_rec.unwrap_or(usize::MAX);
 
         for object in objects {
-            // stream to only read as many rows as needed into memory
-            let stream = read_to_delimited_chunks(store, object).await;
+            let stream = store.get(&object.location).await.unwrap();

Review Comment:
   safe unwrap?



##########
datafusion/core/src/datasource/file_format/file_type.rs:
##########
@@ -111,6 +115,58 @@ impl FileCompressionType {
         self.variant.is_compressed()
     }
 
+    /// Given a `Stream`, create a `Stream` which data are decompressed with `FileCompressionType`.
+    pub fn convert_to_compress_stream<
+        T: Stream<Item = Result<Bytes>> + Unpin + Send + 'static,
+    >(
+        &self,
+        s: T,
+    ) -> Result<Box<dyn Stream<Item = Result<Bytes>> + Send + Unpin>> {
+        #[cfg(feature = "compression")]
+        let err_converter = |e: std::io::Error| match e
+            .get_ref()
+            .and_then(|e| e.downcast_ref::<DataFusionError>())
+        {
+            Some(_) => {
+                *(e.into_inner()
+                    .unwrap()
+                    .downcast::<DataFusionError>()
+                    .unwrap())

Review Comment:
   safe unwraps?



##########
datafusion-examples/examples/csv_sql.rs:
##########
@@ -48,5 +49,22 @@ async fn main() -> Result<()> {
     // print the results
     df.show().await?;
 
+    // query with

Review Comment:
   expand on this comment a bit? seems it was cutoff, so like `query compressed CSV with specific options` etc.



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