spt-delta-core

Core delta types and traits for behavioral vector change tracking

Overview

spt-delta-core provides the fundamental abstractions for computing, applying, and composing deltas on vector data structures. It supports event sourcing via delta streams, time-bounded aggregation via delta windows, and multiple encoding strategies (sparse, dense, run-length, hybrid). This is the foundation for incremental vector updates throughout the SPT database engine.

Key Features

• Vector delta computation -- compute sparse change sets between two vector states
• Delta composition -- combine multiple sequential deltas into a single operation
• Delta streams -- ordered event-sourcing sequences with checkpointing
• Windowed aggregation -- time-bounded delta rollups for analytics
• Compression codecs -- LZ4 and Zstd compression for delta storage (optional)

Dependencies

Key internal dependencies:

• bincode -- binary encoding for compact delta serialization
• smallvec / arrayvec -- stack-allocated collections for zero-alloc hot paths
• parking_lot -- fast mutex for concurrent delta stream access
• simsimd -- SIMD-accelerated distance computation (optional simd feature)
• lz4_flex / zstd -- compression backends (optional compression feature)

Usage

use spt_delta_core::{VectorDelta, DeltaStream};

let old = vec![1.0f32, 2.0, 3.0];
let new = vec![1.1f32, 2.0, 3.5];
let delta = VectorDelta::compute(&old, &new);

let mut reconstructed = old.clone();
delta.apply(&mut reconstructed).unwrap();

API Reference

Core Types

Type	Description
VectorDelta	A computed delta between two vector states
Delta	Trait for types that represent state changes
DeltaOp	Individual delta operation (set, add, remove)
SparseDelta	Delta encoding that only stores changed indices
DeltaStream	Ordered sequence of deltas for event sourcing
StreamCheckpoint	Snapshot point in a delta stream
DeltaWindow	Time-bounded aggregation of deltas
WindowAggregator	Computes rollup statistics over a delta window
DeltaCompressor	Applies compression codecs to serialized deltas
DeltaEncoding	Trait for sparse/dense/hybrid encoding strategies