[Bug] Empty array/map field in Hive text is read as NULL (or errors) instead of an empty collection

Start in be/src/core/data_type_serde/ at DataTypeArraySerDe::deserialize_one_cell_from_hive_text and DataTypeMapSerDe::deserialize_one_cell_from_hive_text, and inspect how empty slices and the explicit \N marker are handled. Verify the change with Hive text deserialization coverage: empty fields should produce [] or {}, while \N remains NULL and non-nullable loads no longer fail.

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Version

master / 4.0

What's Wrong?

When reading a Hive text-format table, an empty field for an ARRAY or MAP column is not deserialized as an empty collection. In DataTypeArraySerDe::deserialize_one_cell_from_hive_text and DataTypeMapSerDe::deserialize_one_cell_from_hive_text (be/src/core/data_type_serde/), an empty slice returns Status::InvalidArgument("slice is empty!"):

• For a nullable column, DataTypeNullableSerDe swallows that error and inserts NULL, so an empty field silently becomes NULL.
• For a non-nullable column, the error propagates and fails the load.

Neither matches Spark/Hive semantics, where an empty complex-type field is an empty collection ([] / {}), distinct from an explicit NULL (\N).

What You Expected?

An empty Hive-text field for an ARRAY/MAP column should deserialize to an empty collection ([] / {}). An explicit NULL marker (\N) should remain NULL.

How to Reproduce?

Query a Hive text table (or use the Hive text serde) where an ARRAY/MAP column has an empty field. The value comes back as NULL (nullable column) or the read fails (non-nullable column), instead of an empty collection.

Anything Else?

Fix: on an empty slice, append an empty collection (a zero-length element) and return OK, instead of returning InvalidArgument. This changes empty nullable array/map fields from NULL to []/{}; explicit \N is unchanged. (Struct is intentionally left out — an "empty struct" has no canonical representation; that can be a follow-up.)

Are you willing to submit PR?

• Yes I am willing to submit a PR!

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