record sparse-vec {
    dim: s32,
    indices: list<s32>,
    values: list<f32>
  }

  variant db-column-type {
    // ...
    vector,
    halfvec,
    sparsevec
  } 

  variant db-value {
    // ...
    vector(list<f32>),
    halfvec(list<f32>), 
    sparsevec(sparse-vec)
  }