Feature Request: Support compound / partitioned VECTOR INDEX (vector + scalar column)

[bjsmiley]

It would be very useful if Azure SQL's VECTOR INDEX could support compound (composite) vector indexes, e.g., indexing on (Embedding, PartitionId) so that nearest neighbor search (VECTOR_SEARCH) can be constrained by a scalar column.

This would be useful for:

• making multiple separate search spaces that still share the same table/schema.
• avoid post filtering after ANN search

Right now the only workaround is to create separate tables per partitionId, adding schema and app logic complexity.

Proposed Idea:
Allow CREATE VECTOR INDEX to accept multiple columns like:

CREATE VECTOR INDEX vec_idx ON [dbo].[wikipedia_articles]([title_vector, partition_id]) 
WITH (METRIC = 'cosine', TYPE = 'diskann');