params.index.json

{
    "k1": 1.5,
    "b": 0.75,
    "delta": 0.5,
    "method": "lucene",
    "idf_method": "lucene",
    "dtype": "float32",
    "int_dtype": "int32",
    "num_docs": 37507469,
    "version": "0.2.1",
    "backend": "numpy"
}