Forum Discussion

Copper Contributor

Jan 07, 2026

Solved

SQL Server 2025 VECTOR functions accepting JSON array strings

Hello! Playing with new VECTOR type and functions, I can read following https://learn.microsoft.com/en-us/sql/t-sql/functions/vector-distance-transact-sql?view=sql-server-ver17 for vector parameters...

sql server

Type Conversion

vectors

carlwalk
Jan 20, 2026
In SQL Server 2025, the new VECTOR functions like VECTOR_DISTANCE work only with actual VECTOR values. You can store a JSON array string in a VECTOR column because SQL Server can convert it when inserting, but the functions won’t automatically convert a JSON string to a VECTOR when you use it. You need to explicitly cast the JSON array to VECTOR first for the functions to work. Essentially, JSON arrays don’t magically become vectors you have to tell SQL Server to treat them that way.

carlwalk

Brass Contributor

Jan 20, 2026

In SQL Server 2025, the new VECTOR functions like VECTOR_DISTANCE work only with actual VECTOR values. You can store a JSON array string in a VECTOR column because SQL Server can convert it when inserting, but the functions won’t automatically convert a JSON string to a VECTOR when you use it. You need to explicitly cast the JSON array to VECTOR first for the functions to work. Essentially, JSON arrays don’t magically become vectors you have to tell SQL Server to treat them that way.