1 unstable release
0.2.0 | Sep 26, 2020 |
---|
#27 in #cql
15KB
80 lines
This crate implements various CqlType derivatives for storing f64
values in a CQL database.
Will allocate 8 bytes per value linked.
Benchmarks
Benchmarks supplied below are fairly rudimentary (and rounded) and are there to give a rough idea of relative costs.
Full benchmark code can be found in github and can be run with
rustup run nightly cargo bench
.
Operation | Database dimensions | Mean time _unchecked (ns) |
---|---|---|
Single point read | 1 | 2 610 (+/- 150) |
Single point read | 4 | 15 500 (+/- 800) |
Single point write | 1 | 2 950 (+/- 250) |
Single point write | 4 | 16 500 (+/- 2 000) |
Stream read 1 point | 1 | 2 600 (+/- 200) |
Stream read 1 point | 4 | 15 400 (+/- 850) |
Stream read 50 000 points | 1 | 27 950 000 (+/- 150 000) |
Stream read 50 000 points | 4 | 27 930 000 (+/- 200 000) |
Examples
The following creates a 1D database, writes 2 values to it, and then streams them into an array.
#
const N_VALUES_TO_READ: usize = 3;
let base_point = [1];
let value1 = 1.2;
let value3 = -5.6;
cql_db::create_db::<F64>(
DATABASE_LOCATION,
&[3]
)?;
cql_db::write_value::<F64>(
DATABASE_LOCATION,
&base_point,
value1
)?;
cql_db::write_value::<F64>(
DATABASE_LOCATION,
&[base_point[0] + 2],
value3
)?;
let mut result: [f64; N_VALUES_TO_READ] = [0.0; N_VALUES_TO_READ];
let mut stream = Cursor::new(Vec::new());
cql_db::read_to_stream::<F64>(
DATABASE_LOCATION,
&mut stream,
&base_point,
N_VALUES_TO_READ as u64
)?;
stream.seek(SeekFrom::Start(0)).unwrap();
unpack_stream(&mut stream, N_VALUES_TO_READ, |idx, value| {
result[idx] = value
})?;
assert_eq!(result[0], value1);
assert_eq!(result[1], 0.0);
assert_eq!(result[2], value3);
Dependencies
~120KB