mysql2/README.rdoc

= Mysql2 - A modern, simple and very fast Mysql library for Ruby, binding to libmysql

The Mysql2 gem is meant to serve the extremely common use-case of connecting, querying and iterating on results.
Some database libraries out there serve as direct 1:1 mappings of the already complex C API's available.
This one is not.

It also forces the use of UTF-8 [or binary] for the connection [and all strings in 1.9] and uses encoding-aware MySQL API calls where it can.

The API consists of two clases:

Mysql2::Client - your connection to the database

Mysql2::Result - returned from issuing a #query on the connection. It includes Enumerable.

== Installing

  gem install mysql2

You may have to specify --with-mysql-lib=/usr/local/lib/mysql or your path to libmysql (I'll do my best to not require that)

== Usage

Connect to a database:

  # this takes a hash of options, almost all of which map directly
  # to the familiar database.yml in rails
  # See http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/MysqlAdapter.html
  client = Mysql2::Client.new(:host => "localhost", :username => "root")

Then query it:

  results = client.query("SELECT * FROM users WHERE group='githubbers'")

Need to escape something first?

  escaped = client.escape("gi'thu\"bbe\0r's")
  results = client.query("SELECT * FROM users WHERE group='#{escaped}'")

Finally, iterate over the results:

  results.each do |row|
    # conveniently, row is a hash
    # the keys are the fields, as you'd expect
    # the values are pre-built ruby primitives mapped from their corresponding field types in MySQL
    # Here's an otter: http://farm1.static.flickr.com/130/398077070_b8795d0ef3_b.jpg
  end

Or, you might just keep it simple:

  client.query("SELECT * FROM users WHERE group='githubbers'").each do |row|
    # do something with row, it's ready to rock
  end

How about with symbolized keys?

  # NOTE: the :symbolize_keys and future options will likely move to the #query method soon
  client.query("SELECT * FROM users WHERE group='githubbers'").each(:symbolize_keys => true) do |row|
    # do something with row, it's ready to rock
  end

== Compatibility

The specs pass on my system (SL 10.6.3, x86_64) in these rubies:

* 1.8.7-p249
* ree-1.8.7-2010.01
* 1.9.1-p378
* ruby-trunk
* rbx-head

== Yeah... but why?

Someone: Dude, the Mysql gem works fiiiiiine.

Me: It sure does, but it only hands you nil and strings for field values. Leaving you to convert
them into proper Ruby types in Ruby-land - which is slow as balls.


Someone: OK fine, but do_mysql can already give me back values with Ruby objects mapped to MySQL types.

Me: Yep, but it's API is considerably more complex *and* is 2-3x slower.

== Benchmarks

Performing a basic "SELECT * FROM" query on a table with 30k rows and fields of nearly every Ruby-representable data type,
then iterating over every row using an #each like method yielding a block:

  # And remember, the Mysql gem only gives back nil and strings.
   user       system     total     real
  Mysql2
   2.080000   0.790000   2.870000 (  3.418861)
  Mysql
   1.210000   0.790000   2.000000 (  4.527824)
  do_mysql
   5.450000   0.980000   6.430000 (  7.001563)