J.D. Hollis jdhollis

xitdb-clj is a new immutable database for Clojure. It can time travel like Datomic, and store data in a single file like SQLite. On its own, though, it has no query language. Enter Datascript...

Datascript is normally an in-memory database, but it lets you use anything as backing storage. What if we combined them?

Datascript's storage feature doesn't tell us exactly what changed, so I added one more trick: Editscript, the diffing library. I use it to figure out how to update the database with the minimal number of changes.

The end result is a sort of mini Datomic that writes to a single file. And yet, this setup can do something Datomic can't: it can branch off of any old copy of the database. The example below reverts to an older copy of the database.

Keep in mind that all reads and writes are incremental. The database is not being loaded into memory at once, so you can use it to

Implementation of Jarke J. van Wijk and Wim A.A. Nuij's smooth and efficient zooming and panning for Polymaps.

Type a place name in the search box, top right, and hit "Go!" to fly there.

	CarrierWave.configure do \|config\|
	...
	end

	Mongoid::Document::ClassMethods.send(:include, DelayedImageProcessing)

	module CarrierWave

	# http://sleeplesscoding.blogspot.com/2011/09/recreate-single-version-of.html
	# Note: is_processing_delayed should be set before calling recreate_version! if the version depends on it.

	; Depends on [com.notnoop.apns/apns "0.1.6"].

	(:import ('com.notnoop.apns APNS))

	(defn send-push-notification [device-token message]
	(let [service (.build (.withSandboxDestination
	(.withCert (APNS/newService) "resources/apns-dev-cert.p12" "password")))
	payload (.build (.alertBody (APNS/newPayload) message))]
	(.push service device-token payload)))

	class OnDestroyMiddleware
	def initialize(app, env)
	@app = app
	end

	def call(env)
	env["config"].vm.provisioners.each do \|provisioner\|
	env.ui.info "Attempting to remove client #{provisioner.config.node_name}"
	`knife client show #{provisioner.config.node_name}`
	if $?.to_i == 0

	module Resque
	module AsyncHandling
	# To disable (in config.after_initialize):
	# Resque::AsyncHandling.enabled = false
	mattr_accessor :enabled
	self.enabled = true

	def handle_asynchronously(original_method, params = { })
	if enabled
	now_method = "#{ original_method }_now"

	gem 'resque', '>= 1.10.0'
	gem 'heroku' # You will need the heroku gem for this too.