This gem allows regular magic DateTime timestamps on ActiveRecord models to be overridden with microsecond timestamps. It is currently only compatible with the MySQL connection adaptor, and rails <= 3.2.13.

Because MySQL < 5.6 has no native support for microseconds (or milliseconds), the timestamp is stored as a BIGINT(20) representing microseconds since the Unix epoch. Alternative formats such as DECIMAL are not supported.

In ActiveRecord, this translates to Bignum, and the column is represented in the schema as :integer, :limit => 8.

There is no automatic conversion from the integer representation and a Time instance. This is left up to the app. However, the gem does provide a to_microseconds method on Ruby's time class to make converting time to integer microseconds easier.

Microsecond timestamps should be specified on any model that uses them with (for example):

use_microtime_for :created_at, :updated_at

Any model that does not declare use_microtime_for will fall back to ActiveRecord's regular timestamps.

A microtimestamps migration helper is provided:

class CreateSomeModel < ActiveRecord::Migration
  def up
    create_table :some_model_table, :force => true do |t|
      ...
      t.microtimestamps
    end
  end
end

This adds the usual created_at and updated_at columns in the microsecond timestamp format. It only supports MySQL. Don't forget to specify use_microtime_for on the model, or you'll end up with seconds in the database instead of microseconds, which is bad.

See examples/migration.rb for an example of migrating from regular timestamps to microtimestamps.

The gem sets ActiveRecord::record_timestamps = false globally and declares ActiveRecord::record_microtimestamps = true. This has the effect of turning off native automatic timestamps entirely, and handing over all control of timestamps to microtimestamps. This could interfere with any other code that depends on explicitly controlling the ActiveRecord::record_timestamps setting.