[GitHub] [beam] TheNeuralBit commented on a change in pull request #16066: Use shorter, numerical indices for dataframe reads.

[GitBox <gi...@apache.org>]

TheNeuralBit commented on a change in pull request #16066:
URL: https://github.com/apache/beam/pull/16066#discussion_r758358147



##########
File path: sdks/python/apache_beam/dataframe/io.py
##########
@@ -521,10 +535,15 @@ def create_tracker(self, restriction):
       return beam.io.restriction_trackers.UnsplittableRestrictionTracker(
           tracker)
 
-  def process(self, readable_file, tracker=beam.DoFn.RestrictionParam()):
+  def process(
+      self, readable_file, path_indices, tracker=beam.DoFn.RestrictionParam()):
     reader = self.reader
     if isinstance(reader, str):
       reader = getattr(pd, self.reader)
+    start_index = (
+        tracker.current_restriction().start +
+        path_indices[readable_file.metadata.path] *
+        10**int(math.log(2**64 // len(path_indices), 10)))

Review comment:
       IIUC, this finds the order of magnitude of `2**64 // len(path_indices)`. So it could be substantially smaller than the largest file we can support (e.g. 9999 -> 1000).
   
   Should there be some logic to handle the case where a file is too large and will produce collisions? I'm not sure what we could do in that case though.

##########
File path: sdks/python/apache_beam/dataframe/io.py
##########
@@ -263,10 +277,10 @@ def expand(self, root):
                 self.kwargs,
                 self.binary,
                 self.incremental,
-                self.splitter)))
+                self.splitter),
+            path_indices=beam.pvalue.AsSingleton(indices_pcoll)))

Review comment:
       Great idea to track the path_indices and use that to avoid collisions.




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