[−][src]Crate cql_f64
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);
Structs
F64 |
Functions
unpack_stream | Unpacks |