[SPARK-53482][SQL] MERGE INTO support for when source has less nested field than target #52347
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… field than target
szehon-ho
commented
Sep 15, 2025
| } else { | ||
| extractArrayValue(arrayData, elementType, | ||
| readSchema.fields(readIndex).dataType) | ||
| val writeType = writeSchema.fields(writeIndex).dataType.asInstanceOf[ArrayType] |
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fix a bug here in InMemoryDataSource schema evolution for struct within arrays
|
Does it work for missing nested fields? |
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What changes were proposed in this pull request?
Support MERGE INTO where source has less fields than target. This is already partially supported as part of: #51698, but only for top level fields. This support it even for nested fields (structs, including within other structs, arrays, and maps)
This patch modifies the MERGE INTO assignment to re-use existing logic in TableOutputResolver to resolve empty values in structs to null or default.
Why are the changes needed?
For cases where source has less fields than target in MERGE INTO, it should behave more gracefully (inserting null values where source field does not exist).
Does this PR introduce any user-facing change?
No, only that this scenario used to fail and will now pass.
How was this patch tested?
Add unit test to MergeIntoTableSuiteBase
Was this patch authored or co-authored using generative AI tooling?
No