xudong963 commented on code in PR #14637: URL: https://github.com/apache/datafusion/pull/14637#discussion_r1959912217
########## datafusion/physical-optimizer/src/enforce_sorting/mod.rs: ########## @@ -246,32 +282,50 @@ fn replace_with_partial_sort( /// This function turns plans of the form /// ```text /// "SortExec: expr=\[a@0 ASC\]", -/// " CoalescePartitionsExec", -/// " RepartitionExec: partitioning=RoundRobinBatch(8), input_partitions=1", +/// " ...nodes..." +/// " CoalescePartitionsExec", +/// " RepartitionExec: partitioning=RoundRobinBatch(8), input_partitions=1", /// ``` /// to /// ```text /// "SortPreservingMergeExec: \[a@0 ASC\]", /// " SortExec: expr=\[a@0 ASC\]", -/// " RepartitionExec: partitioning=RoundRobinBatch(8), input_partitions=1", +/// " ...nodes..." +/// " RepartitionExec: partitioning=RoundRobinBatch(8), input_partitions=1", /// ``` /// by following connections from [`CoalescePartitionsExec`]s to [`SortExec`]s. /// By performing sorting in parallel, we can increase performance in some scenarios. +/// +/// This requires that there are no nodes between the [`SortExec`] and [`CoalescePartitionsExec`] +/// which require single partitioning. Do not parallelize when the following scenario occurs: +/// ```text +/// "SortExec: expr=\[a@0 ASC\]", +/// " ...nodes requiring single partitioning..." +/// " CoalescePartitionsExec", +/// " RepartitionExec: partitioning=RoundRobinBatch(8), input_partitions=1", +/// ``` Review Comment: 💯 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
