viirya commented on code in PR #7723:
URL: https://github.com/apache/arrow-datafusion/pull/7723#discussion_r1342916873
##########
docs/source/user-guide/configs.md:
##########
@@ -87,7 +87,7 @@ Environment variables are read during `SessionConfig`
initialisation so they mus
| datafusion.optimizer.repartition_file_scans | true
| When set to `true`, file groups will be repartitioned to achieve
maximum parallelism. Currently Parquet and CSV formats are supported. If set to
`true`, all files will be repartitioned evenly (i.e., a single large file might
be partitioned into smaller chunks) for parallel scanning. If set to `false`,
different files will be read in parallel, but repartitioning won't happen
within a single file.
|
| datafusion.optimizer.repartition_windows | true
| Should DataFusion repartition data using the partitions keys to
execute window functions in parallel using the provided `target_partitions`
level
|
| datafusion.optimizer.repartition_sorts | true
| Should DataFusion execute sorts in a per-partition fashion and
merge afterwards instead of coalescing first and sorting globally. With this
flag is enabled, plans in the form below `text "SortExec: [a@0 ASC]", "
CoalescePartitionsExec", " RepartitionExec: partitioning=RoundRobinBatch(8),
input_partitions=1", ` would turn into the plan below which performs better in
multithreaded environments `text "SortPreservingMergeExec: [a@0 ASC]", "
SortExec: [a@0 ASC]", " RepartitionExec: partitioning=RoundRobinBatch(8),
input_partitions=1", ` |
-| datafusion.optimizer.bounded_order_preserving_variants | false
| When true, DataFusion will opportunistically remove sorts by
replacing `RepartitionExec` with `SortPreservingRepartitionExec`, and
`CoalescePartitionsExec` with `SortPreservingMergeExec`, even when the query is
bounded.
|
+| datafusion.optimizer.prefer_existing_sort | false
| When true, DataFusion will opportunistically remove sorts when the
data is already sorted, replacing `RepartitionExec` with
`SortPreservingRepartitionExec`, and `CoalescePartitionsExec` with
`SortPreservingMergeExec`, When false, DataFusion will prefer to maximize the
parallelism using `Repartition/Coalesce` and resort the data subsequently with
`SortExec`
|
Review Comment:
```suggestion
| datafusion.optimizer.prefer_existing_sort | false
| When true, DataFusion will opportunistically remove sorts when
the data is already sorted, replacing `RepartitionExec` with
`SortPreservingRepartitionExec`, and `CoalescePartitionsExec` with
`SortPreservingMergeExec`. When false, DataFusion will prefer to maximize the
parallelism using `Repartition/Coalesce` and resort the data subsequently with
`SortExec`
|
```
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