NGA-TRAN commented on issue #18594:
URL: https://github.com/apache/datafusion/issues/18594#issuecomment-3512889922
This is the keys of the problem:
> The display logic can be found in
datafustion/physical-plan/src/repartition/mod.rs:611-650. The preserve_order
field is only displayed when the flag is true. It does not show that order is
preserved when input_partitions=1 which is misleading.
### We need to think about the right display to avoid confusion:
> Order within repartitions is dependent on two things, the preserve_order
flag and input_partition_count
>
> - If the preserve order flag is true then no matter the number of input
partitions the order will be preserved
> - If the preserve order flag is false then order is only preserved if
there is a single input partition
> - Otherwise ordering is not preserved
Good display that includes `preserve_order=true` and `sort_exprs=c@2 ASC`
for the case that preserve order flag is true
` RepartitionExec: partitioning=Hash([c@2], 10), input_partitions=10,
preserve_order=true, sort_exprs=c@2 ASC`
Missing `preserve_order` and the `sort_exprs`. The issue of this one is the
flag preserve_order=false but we still have the order preserved 🙂 . We might
need to think of display to make clear of that
`RepartitionExec: partitioning=Hash([a@1], 2), input_partitions=1`
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