Riak Ruby Client (riak-client) Build Status

riak-client is a rich Ruby client/toolkit for Riak, Basho's distributed database that contains a basic wrapper around typical operations, including bucket manipulation, object CRUD, link-walking, and map-reduce.

Dependencies

Ruby 1.9.3, 2.0, and 2.1 are supported. JRuby in 1.9 and 2.0 modes are also supported. riak-client is not compatible with Ruby 1.8.

riak-client requires i18n, builder, beefcake, and multi_json. The cache store implementation requires ActiveSupport 3 or later.

Development dependencies are handled with bundler. Install bundler (gem install bundler) and run this command to get started:

$ bundle install

Run the RSpec suite using bundle exec:

$ bundle exec rake

Basic Example

require 'riak'

# Create a client interface
client = Riak::Client.new

# Create a client that uses secure Protocol Buffers
client = Riak::Client.new(authentication: {
      # certificate authority to validate the server cert
      ca_file: '/home/zedo/ca.crt',

      # username, required
      user: 'zedo',

      # password for password-based authentication
      password: 'catnip',

      # client-cert authentication parameters support filenames,
      # OpenSSL-compatible string data, or properly initialized
      # OpenSSL objects
      client_ca: '/home/zedo/ca.crt',
      cert: File.read '/home/zedo/zedo.crt',
      key: OpenSSL::PKey::RSA.new(File.read '/home/zedo/zedo.key')
    })

# Automatically balance between multiple nodes
client = Riak::Client.new(:nodes => [
  {:host => '10.0.0.1'},
  {:host => '10.0.0.2', :pb_port => 1234},
  {:host => '10.0.0.3', :pb_port => 5678}
])

# Retrieve a bucket
bucket = client.bucket("doc")  # a Riak::Bucket

# Get an object from the bucket
object = bucket.get_or_new("index.html")   # a Riak::RObject

# Change the object's data and save
object.raw_data = "<html><body>Hello, world!</body></html>"
object.content_type = "text/html"
object.store

# Reload an object you already have
object.reload                  # Works if you have the key and vclock, using conditional GET
object.reload :force => true   # Reloads whether you have the vclock or not

# Access more like a hash, client[bucket][key]
client['doc']['index.html']   # the Riak::RObject

# Create a new object
new_one = Riak::RObject.new(bucket, "application.js")
new_one.content_type = "application/javascript" # You must set the content type.
new_one.raw_data = "alert('Hello, World!')"
new_one.store

Bucket Types

Riak 2 uses bucket types to enable groups of similar buckets to share properties, configuration, and to namespace values within those buckets. Bucket type support is integral to how CRDTs work.

Many operations take type options to perform them with a specific bucket type.

# This example assumes you have a "beverages" bucket type.

coffees = client.bucket 'coffees'

chapadao = coffees.new 'chapadao'
chapadao.data = "Chapadao de Ferro"
chapadao.store type: 'beverages' # stores this in the "beverages" bucket type

coffees.get 'chapadao' # raises error, not found
coffees.get 'chapadao', type: 'beverages' # succeeds

chapadao.reload # raises error, not found
chapadao.reload type: 'beverages' # succeeds

chapadao.delete # silently fails to delete it
coffees.delete 'chapadao' # silently fails to delete it

chapadao.delete type: 'beverages' # deletes it
coffees.delete 'chapadao', type: 'beverages' # deletes it

Map-Reduce Example

# Assuming you've already instantiated a client, get the album titles for The Beatles
results = Riak::MapReduce.new(client).
                add("artists","Beatles").
                link(:bucket => "albums").
                map("function(v){ return [JSON.parse(v.values[0].data).title]; }", :keep => true).run

p results # => ["Please Please Me", "With The Beatles", "A Hard Day's Night", 
          #     "Beatles For Sale", "Help!", "Rubber Soul",
          #     "Revolver", "Sgt. Pepper's Lonely Hearts Club Band", "Magical Mystery Tour", 
          #     "The Beatles", "Yellow Submarine", "Abbey Road", "Let It Be"]

Riak Search Examples

For more information about Riak Search, see the Basho wiki.

# Create a client, specifying the Solr-compatible endpoint
# When connecting to Riak 0.14 and later, the Solr endpoint configuration option is not necessary.
client = Riak::Client.new :solr => "/solr"

# Search the default index for documents
result = client.search("title:Yesterday") # Returns a vivified JSON object
                                          # containing 'responseHeaders' and 'response' keys
result['response']['numFound'] # total number of results
result['response']['start']    # offset into the total result set
result['response']['docs']     # the list of indexed documents

# Search the 'users' index for documents
client.search("users", "name:Sean")

# Add a document to an index
client.index("users", {:id => "sean@basho.com", :name => "Sean Cribbs"}) # adds to the 'users' index

client.index({:id => "index.html", :content => "Hello, world!"}) # adds to the default index

client.index({:id => 1, :name => "one"}, {:id => 2, :name => "two"}) # adds multiple docs

# Remove document(s) from an index
client.remove({:id => 1})             # removes the document with ID 1
client.remove({:query => "archived"}) # removes all documents matching query
client.remove({:id => 1}, {:id => 5}) # removes multiple docs

client.remove("users", {:id => "sean@basho.com"}) # removes from the 'users' index

# Seed MapReduce with search results
Riak::MapReduce.new(client).
        search("users","email:basho").
        map("Riak.mapValuesJson", :keep => true).
        run

# Detect whether a bucket has auto-indexing
client['users'].is_indexed?

# Enable auto-indexing on a bucket
client['users'].enable_index!

# Disable auto-indexing on a bucket
client['users'].disable_index!

Secondary Index Examples

Riak supports secondary indexes. Secondary indexing, or "2i," gives you the ability to tag objects with multiple queryable values at write time, and then query them later.

Tagging Objects

Objects are tagged with a hash kept behind the indexes method. Secondary index storage logic is in lib/riak/rcontent.rb.

object = bucket.get_or_new 'cobb.salad'

# Indexes end with the "_bin" suffix to indicate they're binary or string 
# indexes. They can have multiple values.
object.indexes['ingredients_bin'] = %w{lettuce tomato bacon egg chives}

# Indexes ending with the "_int" suffix are indexed as integers. They can
# have multiple values too.
object.indexes['calories_int'] = [220]

# You must re-save the object to store indexes.
object.store

Finding Objects

Secondary index queries return a list of keys exactly matching a scalar or within a range.

# The Bucket#get_index method allows querying by scalar...
bucket.get_index 'calories_int', 220 # => ['cobb.salad']

# or range.
bucket.get_index 'calories_int', 100..300 # => ['cobb.salad']

# Binary indexes also support both ranges and scalars.
bucket.get_index 'ingredients_bin', 'tomata'..'tomatz' # => ['cobb.salad']

# The collection from #get_index also provides a continuation for pagination:
c = bucket.get_index 'ingredients_bin', 'lettuce', max_results: 5
c.length # => 5
c.continuation # => "g2gCbQAAA="

# You can use that continuation to get the next page of results:
c2 = bucket.get_index 'ingredients_bin', 'lettuce', max_results: 5, continuation: c.continuation

# More complicated operations may benefit by using the `SecondaryIndex` object:
q = Riak::SecondaryIndex.new bucket, 'ingredients_bin', 'lettuce', max_results: 5

# SecondaryIndex objects give you access to the keys...
q.keys # => ['cobb.salad', 'wedge.salad', 'buffalo_chicken.wrap', ...]

# but can also fetch values for you in parallel.
q.values # => [<RObject {recipes,cobb.salad} ...>, <RObject {recipes,wedge...

# They also provide simpler pagination:
q.has_next_page? # => true
q2 = q.next_page

Riak 2 Data Types

Riak 2 features new distributed data structures: counters, sets, and maps (containing counters, flags, maps, registers, and sets). These are implemented by the Riak database as Convergent Replicated Data Types.

Riak data type support requires bucket types to be configured to support each top-level data type. If you're just playing around, use the Riak Ruby Vagrant setup to get started with the appropriate configuration and bucket types quickly.

The examples below presume that the appropriate bucket types are named counters, maps, and sets; these bucket type names are the client's defaults. Viewing and changing the defaults is easy:

Riak::Crdt::DEFAULT_BUCKET_TYPES[:set] #=> "sets"

Riak::Crdt::DEFAULT_BUCKET_TYPES[:set] = "a_cooler_set"

The top-level CRDT types have both immediate and batch mode. If you're doing multiple writes to a single top-level counter or set, or updating multiple map entries, batch mode will make fewer round-trips to Riak.

Top-level CRDT types accept nil as a key. This allows Riak to assign a random key for them.

Deleting CRDTs requires you to use the key-value API for the time being.

brews = Riak::Crdt::Set.new bucket, 'brews'
brews.add 'espresso'
brews.add 'aeropress'

bucket.delete brews.key, type: brews.bucket_type

Counters

Riak 2 integer counters have one operation: increment by an integer.

counter = Riak::Crdt::Counter.new bucket, key

counter.value #=> 15

counter.increment

counter.value #=> 16

counter.increment 3

counter.value #=> 19

counter.decrement

counter.value #=> 18

Counter operations can be batched:

counter.batch do |c|
  c.increment
  c.increment 5
end

Maps

Riak 2 maps can contain counters, flags (booleans), registers (strings), sets, and other maps.

Maps are similar but distinct from the standard Ruby Hash. Entries are segregated by both name and type, so you can have counters, registers, and sets inside a map that all have the same name.

map = Riak::Crdt::Map.new bucket, key

map.counters['potatoes'].value #=> 5
map.sets['potatoes'].include? 'yukon gold' #=> true

map.sets['cacti'].value #=> #<Set: {"saguaro", "prickly pear", "fishhook"}>
map.sets['cacti'].remove 'prickly pear'

map.registers['favorite butterfly'] = 'the mighty monarch'

map.flags['pet cat'] = true

map.maps['atlantis'].registers['location'] #=> 'kennedy space center'

map.counters.delete 'thermometers'

Maps are a prime candidate for batched operations:

map.batch do |m|
  m.counters['hits'].increment
  m.sets['followers'].add 'basho_elevator'
end

Frequently, you might want a map with a Riak-assigned name instead of one you come up with yourself:

map = Riak::Crdt::Map.new bucket, nil

map.registers['coat_pattern'] = 'tabby'

map.key #=> "2do4NvcurWhXYNQg8HoIR9zedJV"

Sets

Sets are an unordered collection of entries.

PROTIP: Ruby and Riak Ruby Client both have classes called Set. Be careful to refer to the Ruby version as ::Set and the Riak client version as Riak::Crdt::Set.

set = Riak::Crdt::Set.new bucket, key

set.members #=> #<Set: {"Edinburgh", "Leeds", "London"}>

set.add "Newcastle"
set.remove "London"

set.include? "Leeds" #=> true

Sets support batched operations:

set.batch do |s|
  s.add "York"
  s.add "Aberdeen"
  s.remove "Newcastle"
end

Client Implementation Notes

The client code for these types is in the Riak::Crdt namespace, and mostly in the lib/riak/crdt directory.

Riak 1.4 Counters

For more information about counters in Riak, see the Basho wiki.

Counter records are automatically persisted on increment or decrement. The initial default value is 0.

# Firstly, ensure that your bucket is allow_mult set to true
bucket = client.bucket "counters"
bucket.allow_mult = true

# You can create a counter by using the bucket's counter method
counter = bucket.counter("counter-key-here")
counter.increment
=> nil

p counter.value
1
=> 1

# Let's increment one more time and then retrieve it from the database
counter.increment

# Retrieval is similar to creation
persisted_counter = Riak::Counter.new(bucket, "counter-key-here")

p persisted_counter.value
2
=> 2

# We can also increment by a specified number
persisted_counter.increment(20)
p persisted_counter.value
22
=> 22

# Decrement works much the same
persisted_counter.decrement
persisted_counter.value
=> 21

persisted_counter.decrement(6)
persisted_counter.value
=> 15

# Incrementing by anything other than integer will throw an ArgumentError
persisted_counter.increment "nonsense"
ArgumentError: Counters can only be incremented or decremented by integers.

That's about it. PN Counters in Riak are distributed, so each node will receive the proper increment/decrement operation. Enjoy using them.

How to Contribute

License & Copyright

Copyright ©2010-2012 Sean Cribbs and Basho Technologies, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Auxillary Licenses

The included photo (spec/fixtures/cat.jpg) is Copyright ©2009 Sean Cribbs, and is licensed under the Creative Commons Attribution Non-Commercial 3.0 license. "Creative Commons"