Which operation is NOT permitted on tables containing VECTOR columns?

The operation that is not permitted on tables containing VECTOR columns is specifically joining on those vector columns. Vector columns are designed to store high-dimensional data that represents complex entities such as images or texts for AI applications. Due to the nature of vector representations, which may involve specific mathematical properties and calculations, traditional SQL operations like JOIN that expect precise equality or range comparisons are not applicable.

When you attempt to perform a join on vector columns, the database cannot guarantee appropriate match semantics since vectors are often compared based on similarity rather than direct equality. As a result, standard SQL join semantics don’t work effectively with high-dimensional data stored as vectors. In contrast, operations like SELECT, UPDATE, and DELETE are permissible as they can work with the metadata or the attributes associated with the vector columns, without directly manipulating or comparing the vector data itself.