reifydb_value/value/partition/
mod.rs

1// SPDX-License-Identifier: Apache-2.0
2// Copyright (c) 2026 ReifyDB
3
4use postcard::to_extend;
5use serde::{Deserialize, Serialize};
6
7use super::Value;
8use crate::util::hash::xxh3_128;
9
10#[repr(transparent)]
11#[derive(Default, Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
12#[serde(transparent)]
13pub struct Partition(pub u128);
14
15impl Partition {
16	/// Seedless `xxh3_128` over the concatenated postcard encodings, so the partition of a row is
17	/// identical on every node and across restarts. Values are appended without a separator, which
18	/// only stays unambiguous because postcard is self-delimiting.
19	pub fn of(values: &[Value]) -> Self {
20		let mut buf: Vec<u8> = Vec::new();
21		for value in values {
22			buf = to_extend(value, buf).expect("postcard serialization of a Value is total");
23		}
24		Partition(xxh3_128(&buf).0)
25	}
26}
27
28impl From<u128> for Partition {
29	fn from(value: u128) -> Self {
30		Partition(value)
31	}
32}
33
34#[cfg(test)]
35mod tests {
36	use super::*;
37
38	#[test]
39	fn test_deterministic() {
40		let a = Partition::of(&[Value::Utf8("us".to_string())]);
41		let b = Partition::of(&[Value::Utf8("us".to_string())]);
42		assert_eq!(a, b, "same values must hash to the same partition");
43	}
44
45	#[test]
46	fn test_distinct_values_distinct_partition() {
47		let us = Partition::of(&[Value::Utf8("us".to_string())]);
48		let eu = Partition::of(&[Value::Utf8("eu".to_string())]);
49		assert_ne!(us, eu, "different values should (overwhelmingly) hash differently");
50	}
51
52	#[test]
53	fn test_multi_column() {
54		let a = Partition::of(&[Value::Utf8("us".to_string()), Value::Uint8(1)]);
55		let b = Partition::of(&[Value::Utf8("us".to_string()), Value::Uint8(2)]);
56		assert_ne!(a, b);
57	}
58}
reifydb_value/value/partition/mod.rs

reifydb_value/value/partition/
mod.rs
