create_vector_index
Create a vector index on a vector type field in the Mochow instance.
Args:
table_name (str): Name of the table.
index_name (str): Name of the index.
field_name (str): Name of the vector field.
index_type (str): Type of vector index. Supported values are "HNSW", "HNSWPQ", "HNSWSQ".
metric_type (str): Distance metric. Supported values are "L2", "COSINE", "IP".
params (Optional[dict[str, Any]]): Additional vector index parameters.
Returns:
str: A message indicating the success of index creation.