Mark Watson's opinions on Java, Ruby, Lisp, AI, and the Semantic Web

After I finish up some client work this morning, I am planning on finishing a DevX article on using Heroku as a deployment platform. Since deploying to Heroku is so simple and so well documented, you might think that I would have a difficult time writing new material :-)

After a short tutorial on getting started, I am writing mostly about using both CouchDB and MongoDB as data store, either hosted yourself on EC2 (or another server external to Heroku, which is itself hosted on EC2) or commercial managed solutions like Cloudant for CouchDB and MongoHQ for a managed MongoDB service.

I like to manage my own and customer deployments on EC2 - frankly, it is fun :-)

That said, I think that there are sometimes business reasons for using hosted solutions like Heroku, Cloudant, and MongoHQ. It is a balance between development and admin costs and paying for managed platform as a service offerings.

Labels: CouchDB, MongoDB

I have been spoiled by great support for indexing and search in relational databases (e.g., Sphinx, native search in PostgreSQL and MySQL, etc.)

I was pleased to discover, after a little bit of hacking this morning, how easy it is to do indexing and search using the MongoDB document-centered database. I have two common use cases for search, and MongoDB seems to handle both of them fairly well:

• Search for words inside of text fields
• Efficient word prefix search to support AJAX "suggest" style lists

My approach does require combining search results for multiple search terms in application code, but that is OK. Assuming the use of MongoRecord, here is a code snippet:

class Recipe < MongoRecord::Base
  collection_name :recipes
  fields :name, :directions, :words
  def to_s
    "recipe: #{name} directions: #{directions[0..20]}..."
  end
  def Recipe.make collection, name, directions
    collection.insert({:_id => Mongo::ObjectID.new, :name => name,
                       :directions => directions,
                       :words => (name + ' ' + directions).split.uniq})
  end
end
 
host = 'localhost'
port = Mongo::Connection::DEFAULT_PORT
MongoRecord::Base.connection = Mongo::Connection.new(host,port).db('mongorecord-test')

db = MongoRecord::Base.connection

coll = db.collection('recipes')
coll.remove({})

coll.create_index(:words, Mongo::ASCENDING)

Recipe.make coll, 'Rice Soup', 'Cook the rice, then add extra water to thin it out.'
Recipe.make coll, 'Cheese and Rice Crackers', 'Slice the cheese and layer on top of crackers.'

puts "\nSimple find"
puts Recipe.find_by_name(:name => 'Rice Soup').to_s

puts "\nFind recipe by regular expression (ignoring case) in array of words /water/i"
Recipe.find(:all, :conditions => {:words => /^water/i}).each { |row| puts row.to_s }

According to the MongoDB documentation, a regular expression match like /^water/i will use an index just as a relational database match in the form like 'water%' does.

I am still in a learning mode with MongoDB, so I would appreciate any comments on improving this aproach.

Labels: MongoDB, Ruby, search

I spend a lot of time experimenting with infrastructure software, sometimes for customer jobs and sometimes just because it is fun to learn new things. For non-SQL data stores, I have spent a lot of time in the last year experimenting with and using CouchDB, AppEngine datastore, Tokyo Cabinet, MongoDB, Cassandra, and SimpleDB. Tokyo Cabinet and SimpleDB store hash values as strings, and don't have the great client APIs that the others have because limitations in string-only hash values. That said, for an Amazon hosted application SimpleDB can be a good choice and Tokyo Cabinet is light weight and easy to install and use. Casandra looks great, and as I have written about here before, Cassandra is easy to use from ruby and has great features.

MongoDB has great performance and similar capabilities as Casandra. Chris Kampmeier has a great writeup that covers installing MongoDB on OS X, including setting it up as a system service. I followed Chris's directions. A pleasant surprise is that MongoDB has a light footprint, and leaving it running as a service like I do with PostgreSQL and MySQL is reasonable.

Along with the mongo and mongo_record gems, MongoDB is an awesome tool, and always keeping it running makes it easy to experiment with. BTW, I also keep Sesame and CouchDB running on my local network for much the same reasons.

Labels: MongoDB, no-SQL, Ruby