Crate cql_tiny_text

This crate implements various CqlType derivatives for storing String values of up to (and including) 255 chars in a CQL database.

Will allocate 1020 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, but please be aware that they will allocate ~102MB of disk space. The read_to_stream benchmarks also differ slightly from other CqlType derivatives as they stream into a Vector, not an Array.

Operation	Chars in String	Database dimensions	Mean time (ns)
Single point read	1	1	2 240 (+/- 185)
Single point read	255	1	2 290 (+/- 350)
Single point read	1	4	11 600 (+/- 2 000)
Single point read	255	4	11 670 (+/- 4 400)
Single point write	1	1	4 070 (+/- 300)
Single point write	255	1	4 180 (+/- 350)
Single point write	1	4	15 100 (+/- 2 200)
Stream read 1 point	1	1	2 300 (+/- 500)
Stream read 1 point	255	1	2 300 (+/- 500)
Stream read 1 point	1	4	11 550 (+/- 2 400)
Stream read 50 000 points	1	1	33 524 000 (+/- 540 000)
Stream read 50 000 points	255	1	33 527 000 (+/- 650 000)
Stream read 50 000 points	1	4	43 082 000 (+/- 867 000)
Stream read 50 000 points	255	4	43 600 000 (+/- 1 787 000)

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 = [0];
let value1 = "item one";
let value3 = "شماره ۳";

cql_db::create_db::<TinyText>(
    DATABASE_LOCATION,
    &[3]
);

cql_db::write_value::<TinyText>(
    DATABASE_LOCATION,
    &base_point,
    value1.to_string()
);

cql_db::write_value::<TinyText>(
    DATABASE_LOCATION,
    &[base_point[0] + 2],
    value3.to_string()
);

let mut result = Vec::with_capacity(N_VALUES_TO_READ);
let mut stream = Cursor::new(Vec::new());

cql_db::read_to_stream::<TinyText>(
    DATABASE_LOCATION,
    &mut stream,
    &base_point,
    N_VALUES_TO_READ as u64
);

stream.seek(SeekFrom::Start(0));
unpack_stream(&mut stream, N_VALUES_TO_READ, |_, value| {
    result.push(value)
});

assert_eq!(result[0], value1.to_string());
assert_eq!(result[1], String::new());
assert_eq!(result[2], value3.to_string());

Structs

TinyText

Static struct for declaring that you want to work with TinyText values in a CQL database.

Functions

unpack_stream

Unpacks n_values of String from a stream, calling res with each value and it's index.