Vector Indexes

Question

I have a database table with a Vector Column in SQL Server 2025 but unable to use the Create Vector Index Command

Answer 1

To be able to create vector indexes, you need to enable the database for preview features:

ALTER DATABASE SCOPED CONFIGURATION SET PREVIEW_FEATURES = ON

Answer 2

Hi Bradley ,

Additionally, you might also want to check

1. It’s a base table (not a view or temp table) because vector indexes only work on base tables.
   2 The target column isn’t declared as VECTOR(n [ , base_type])
   3.You may be on an older RC/CTP, or using SSMS before 21.x. Update both engine and SSMS
   4.Query metric doesn’t match the index metric; or query shape/filters force a fallback to exact distance. Align metrics (e.g., cosine with cosine) and check your query.

Reference- https://learn.microsoft.com/en-us/sql/t-sql/statements/create-vector-index-transact-sql?view=sql-server-ver17

Hope this helps!

Answer 3

If you are unable to use the CREATE VECTOR INDEX command in SQL Server 2025, ensure that you are following the correct syntax and that your database is configured to support vector features. The command should be executed in a context where the vector column is properly defined in your table. Here’s a brief overview of how to create a vector index:

1. Define a Vector Column: Make sure your table has a vector column defined correctly using the VECTOR data type.
2. Create the Vector Index: Use the CREATE VECTOR INDEX command with the appropriate parameters to create the index on your vector column.

If you continue to face issues, check for any limitations or constraints that might be affecting the creation of the index, such as the absence of necessary permissions or compatibility settings in your SQL Server instance.

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References:

• Vector search and vector indexes in the SQL Database Engine
• Vector data type