[GitHub] [arrow-datafusion] alamb commented on a diff in pull request #5898: Minor: Improve doc comments in FileStream

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

alamb commented on code in PR #5898:
URL: https://github.com/apache/arrow-datafusion/pull/5898#discussion_r1161792996


##########
datafusion/core/src/physical_plan/file_format/file_stream.rs:
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@@ -140,14 +141,31 @@ impl StartableTime {
     }
 }
 
+/// Metrics for [`FileStream`]
+///
+/// Note that all of these metrics are in terms of wall clock time
+/// (not cpu time) so they include time spent waiting on I/O as well
+/// as other operators.
 struct FileStreamMetrics {
-    /// Time elapsed for file opening
+    /// Wall clock time elapsed for file opening.
+    ///
+    /// Time between when [`FileReader::open`] is called and when the
+    /// [`FileStream`] receives a stream for reading.
     pub time_opening: StartableTime,
-    /// Time elapsed for file scanning + first record batch of decompression + decoding
+    /// Wall clock time elapsed for file scanning + first record batch of decompression + decoding
+    ///
+    /// Time between when the [`FileStream`] requests data from the
+    /// stream and when the first [`RecordBatch`] is produced.
     pub time_scanning_until_data: StartableTime,
-    /// Total elapsed time for for scanning + record batch decompression / decoding
+    /// total elapsed wall clock time for for scanning + record batch decompression / decoding
+    ///
+    /// Sum of time between when the [`FileStream`] requests data from
+    /// the stream and when a [`RecordBatch`] is produced for all
+    /// record batches in the stream.
     pub time_scanning_total: StartableTime,

Review Comment:
   Updated in 94ecfc49fa



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