issue: #43980
Fixes a panic that occurred when a partial update was converted to an
insert due to a non-existent primary key. The panic was caused by
missing nullable fields that were not provided in the original partial
update request.
The upsert pre-execution logic is refactored to handle this correctly:
- Explicitly splits upsert data into 'insert' and 'update' batches.
- Automatically generates data for missing nullable or default-value
fields during inserts, preventing the panic.
- Enhances `typeutil.UpdateFieldData` to support different source and
destination indexes for flexible data merging.
- Adds comprehensive unit tests for mixed upsert, pure insert, and pure
update scenarios.
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Signed-off-by: Wei Liu <wei.liu@zilliz.com>
16af4e230a