Nemesis DB

Nemesis DB is an open source port of Bustle's Gradius graph database.

Intro

This is a simple adjacency graph database with only a few features. It has been designed for very fast reads. While it handles writes with ease whenever a tradeoff favors reads, that tradeoff will be taken.

Features

• 32 bit GUID
• Schemaless Nodes
• Weighted Edges
• Compression

Future Features

• Node Schemas, types and Interfaces
• filtering edges based upon weight
• Deleting
• Edge Schemas
• Field Validations
• Edge Validations
• Edge scanning
• Node scanning
• Named Edges
• Field Indexing
• Binary packing

Examples

import { Graph } from 'nememis-db'
 
const graph = new Graph('redis://localhost/1')
 
const book = await graph.createNode({ title: 'foo', pages: 24 })
assert.deepEqual(book, { id: 1, title: 'foo', pages: 24 })
 
// update the data of an existing node
const updatedBook = await graph.updateNode({ id: book.id, title: 'bar' })
assert.deepEqual(updatedBook, { id: 1, title: 'bar', pages: 24 })
 
// replace the data of an existing node
const replacedBook = await graph.putNode({ id: book.id, title: 'foo' })
assert.deepEqual(replacedBook, { id: 1, title: 'foo' })
 
const author = await graph.createNode({ name: 'james' })
assert.deepEqual(author, { id: 2, name: 'james' })
 
// connect the book and it's author
const edge = await graph.createEdge({ subject: book.id, predicate: 'BookHasAuthor', object: author.id })
assert.deepEqual(edge, { subject: 1, predicate: 'BookHasAuthor', object: 2, weight: 0 })
 
const authors = await graph.findEdges({ subject: book.id, predicate: 'BookHasAuthor' })
assert.deepEqual(authors, [{ subject: 1, predicate: 'BookHasAuthor', object: 2, weight: 0 }])
const object = await graph.findNode(authors[0].object)
assert.deepEqual(object, { id: 2, name: 'james' })
 
// Get an async iterator of all the nodes
for await (node of graph.allNodes()) {
  console.log(node)
}
// { id: 1, title: 'foo' }
// { id: 2, name: 'james' }
 
// use streaming-iterables to make an array of the async iterator
const allNodes = await collect(graph.allNodes())
assert.deepEqual(allNodes, [{ id: 1, title: 'foo' }, { id: 2, name: 'james' }])

API Type Defs

export declare class Graph {
    readonly config: GraphConfig;
    readonly messagePack: messagePack.MessagePack;
    readonly redis: Redis.Redis;
    constructor(redisUrl: string, config?: GraphConfigInput);
    allNodes({ batchSize }?: NodeScanOptions): AsyncIterableIterator<Node>;
    createEdge({ subject, predicate, object, weight }: EdgeInput): Promise<Edge>;
    createNode(attributes: any): Promise<Node>;
    disconnect(): void;
    findEdges(edge: SubjectEdgeSearch | ObjectEdgeSearch): Promise<ReadonlyArray<Edge>>;
    findNode(id: number): Promise<Node | null>;
    nodeExists(id: number): Promise<boolean>;
    putNode(node: Node): Promise<Node>;
    updateNode(node: Node): Promise<Node>;
    private evalCommands;
    private evalCreateEdge;
    private getNextId;
    private nodeKey;
}
 
export interface Node {
    readonly id: number;
    readonly [key: string]: any;
}
export interface GraphConfigInput {
    readonly compressors?: ReadonlyArray<Compressor>
    readonly edgePrefix?: string;
    readonly guidKey?: string;
    readonly nodeIndexKey?: string;
    readonly nodeKeyPrefix?: string;
}
export interface GraphConfig {
    readonly edgePrefix: string;
    readonly guidKey: string;
    readonly nodeIndexKey: string;
    readonly nodeKeyPrefix: string;
}
export interface EdgeInput {
    readonly object: number;
    readonly predicate: string;
    readonly subject: number;
    readonly weight?: number;
}
export interface Edge {
    readonly object: number;
    readonly predicate: string;
    readonly subject: number;
    readonly weight: number;
}
export interface SubjectEdgeSearch {
    readonly limit?: number;
    readonly offset?: number;
    readonly predicate: string;
    readonly subject: number;
}
export interface ObjectEdgeSearch {
    readonly limit?: number;
    readonly object: number;
    readonly offset?: number;
    readonly predicate: string;
}
export interface NodeScanOptions {
    readonly batchSize?: number;
}
export interface Compressor {
    readonly compress: (Buffer: any) => Buffer | Promise<Buffer>;
    readonly decompress: (Buffer: any) => Buffer | Promise<Buffer>;
    readonly name: string;
}

Developing

Tests use your local redis db 2 by default and are destructive. To use another DB submit a patch to make this configurable.