Allow InterleaveExec to preserve Partitioning::Range #23455

Related:

• #22395
• #21992
• #23184
• #23266

Is your feature request related to a problem or challenge?

UnionExec does not preserve partitioning metadata. It concatenates child partitions and reports UnknownPartitioning(total_input_partitions), which is right because equal range keys from different children can land in different output partitions.

InterleaveExec is the partition-aware variant. This operator takes output partition i and combines partition i from each child. It preserves partitioning only when children have identical hash partitioning. This shoudl be extended to range partitioning

Example

InterleaveExec
  DataSourceExec: output_partitioning=Range([range_key@0 ASC], [(10), (20)], 3)
  DataSourceExec: output_partitioning=Range([range_key@0 ASC], [(10), (20)], 3)

Partition i of InterleaveExec combines partition i from each child, so compatible range boundaries can remain valid.

Describe the solution you'd like

Allow InterleaveExec to preserve Partitioning::Range when all children are compatible by partition index.

Acceptance criteria

• Keep UnionExec conservative: it should continue to report unknown partitioning for concatenated child partitions.
• Remove the current SLT test that expects it to preserve range (I was mistaken originally on its behavior)
• Allow InterleaveExec for compatible range children.
• Require co-partitioned children.
• Fall back to UnknownPartitioning for mixed or incompatible inputs.
• Add tests for compatible range children, incompatible boundaries, and mixed partitioning.

Additional context