Riak is a distributed key/value store. It is really cool. Unfortunately, shy of deleting the data file entirely, clearing out a bucket is dog slow, poorly documented, and pretty ugly with the ruby driver.

Sure, you could argue that if you have the need to clear out lots of entries at once from a Riak KV store, your problem space may not be well suited for a KV store. Still, it isn’t a completely unreasonable thing to do but with Ripple and the ruby driver, the only way to clear a bucket is to load all keys into memory and then delete each. Seriously. That sucks. I’ve spoken with Sean Cribbs, the gem’s author, about this before and I’m pretty convinced this might be a limitation of Riak rather than the library. Either way, if you need to delete everything from a bucket, make sure you understand that it will take a long time and potentially use a lot of memory.

One great example of when you would want to clear a bucket is as a setup task for specs:

RSpec.configure do |config|
  config.before(:each) do
    Notification.bucket.keys.each {|k| Notification.bucket.delete(k)}
  end
end

I hope you like slow test suites!

Edit

Turns out there is a subtle but more efficient way to do this. Thanks to Aphyr

RSpec.configure do |config|
  config.before(:each) do
    Notification.bucket.keys {|keys| keys.each {|k|Notification.bucket.delete(k)}
  end
end

Evidently that extra block scoping streams the keys. Neat!