fix: CAST(MapType AS MapType) falls back even though native ...#4559
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gittihub-jpg wants to merge 1 commit into
Open
fix: CAST(MapType AS MapType) falls back even though native ...#4559gittihub-jpg wants to merge 1 commit into
gittihub-jpg wants to merge 1 commit into
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…#4491) Fixes apache#4491 Signed-off-by: gittihub-jpg <rico@springer-mail.net>
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Thanks @gittihub-jpg. The changes look reasonable but I don't see any tests in the PR? |
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Closes #4491.
Rationale for this change
CometCast.isSupported lacks a MapType arm, so any cast involving map types hits the default case and falls back to Spark. The native implementation already supports map-to-map conversion via cast_map_to_map in cast.rs. Routing Scala casts to this function removes unnecessary fallbacks and improves execution performance.
What changes are included in this PR?
Add a case for (MapType, MapType) in CometCast.isSupported. The new logic recursively checks key types and value types using isSupported. It returns Compatible when both recursive checks pass, or Incompatible with a descriptive reason string otherwise. No Rust changes are required since the native cast_map_to_map function already exists.
How are these changes tested?
Existing unit tests for CometCast cover type compatibility checks. The new MapType branch is validated by running the full test suite and verifying that map-to-map casts no longer trigger a fallback to Spark.