[SPARK-58221] Add try_variant_set expression

[bojana-db]

What changes were proposed in this pull request?

Adds the SQL function try_variant_set(v, path, val[, create_if_missing]), the error-tolerant counterpart of variant_set (SPARK-57804). It sets (inserts or replaces) a value in a Variant value at a single JSONPath location, returning NULL instead of failing the query when the operation hits a recoverable error.

Details:

• On a valid set, behaves exactly like variant_set: an object path (e.g. $.a) replaces the field if it exists and creates it when create_if_missing is true (the default); an array path (e.g. $[N]) replaces the element at index N, and when N is at or past the end and create_if_missing is true, pads the array with variant nulls up to N; missing intermediate keys/indices along the path are created when create_if_missing is true;
• When create_if_missing is false, a missing leaf, a missing intermediate, or an out-of-range array index leaves v unchanged;
• Recoverable errors are caught and return NULL instead of throwing: any path type mismatch (VARIANT_PATH_TYPE_MISMATCH, e.g. an object key applied to an array);
• Non-recoverable errors still throw, matching variant_set: a malformed path, including the root path $, is rejected with INVALID_VARIANT_PATH (the path is parsed before the set), and a result exceeding the size limit raises VARIANT_SIZE_LIMIT;
• Any NULL argument returns NULL;
• The value may be any expression castable to variant.

Why are the changes needed?

Error-tolerant counterpart of variant_set, matching try_variant_get, try_variant_insert, and other try_* functions.

Does this PR introduce any user-facing change?

Yes, a new SQL function try_variant_set (and the corresponding Scala/Python functions API).

How was this patch tested?

Unit tests.

Was this patch authored or co-authored using generative AI tooling?

Generated-by: Cursor with Claude Opus 4.8

[harshmotw-db]

LGTM, thanks for the feature!

[harshmotw-db]

Should just be "Upsert" or "Sets and inserts" IMO. Upserts is already a combination of insert and update

[harshmotw-db]

Same here

[harshmotw-db]

Some more places as well