README.md

Fast Read-Only Annoy

Introduction

This version of Annoy in Go can only be used to load and query Angular indexes created using Annoy. I only needed Annoy for loading indexes and querying vectors, So I optimized it to be faster with caching and in-memory storage of nodes instead of mmap which Annoy does.

You can tell the index to use mmap or memory. using memory with caching it provides lets your queries to be up to twice as fast as native C++ version of Annoy.

Example

import (
	"fmt"
	"testing"
	"time"

	"github.com/AlisaLC/annoy-go"
)

func main() {
    index := annoy.NewAnnoyIndex[annoy.Angular](20)
    index.Load("test.ann", true)
    vector := []float32{
        -19.206135, -0.29148674, -0.19988513, -3.682283,
        11.192975, 8.732752, 3.024612, 3.606107,
        -5.8107805, 7.36837, 3.0414157, -7.0733867,
        -1.7415776, 2.3138094, -14.7966385, -0.75848556,
        8.763108, -1.8256252, 6.524804, -0.6752771,}
    results, distances := index.GetNnsByVector(vector, 1000, -1)
    // first run can be slower since caching is happening.
    // next runs becomes much faster
}