level-sync

level-sync performs one-way sync between two levelup-compatible data stores, by reading streamed data from both, merging the data into diff operations, and then writing those operations to the target store.

Example

import levelup from "levelup"
import memdown from "memdown"
import sync from "level-sync"

let hours = {
  old: {FRI: "10-7pm", SAT: "10-7pm"},
  new: {SAT: "10-7pm", SUN: "10-7pm"}
}

let local = levelup("", {db: memdown})
let remote = levelup("", {db: memdown})

for (let day in hours.old) remote.put(day, hours.old[day])
for (let day in hours.new) local.put(day, hours.new[day])

let ops = sync(local, remote)

ops.on("data", console.log)
// { type: 'del', key: 'FRI' }
// { type: 'put', key: 'SUN', value: '10-7pm' }

ops.on("end", () => remote.createReadStream().on("data", console.log))
// { key: 'SAT', value: '10-7pm' }
// { key: 'SUN', value: '10-7pm' }

Installation

npm install level-sync

API

let rs = sync(from, to, [options])

Syncs data from the from store to the to store. This works by reading in both stores, diffing them into operations, and then writing the operations to the to store, as well as emitting them to the returned readable stream. If the dryRun property of the optional options object is true, the operations are only emitted, and not written to the target store.