Indexes are now *NOT* created by default in Mongoid.

Also added rake db:create_indexes that will force mongoid to create the indexes on your database (may take a long time).

If you want the old functionality, just set autocreate_indexes to true (via yml, or direct config). The recommended behavior though is to keep this turned off, and create indexes manually via mongodb.

lib/mongoid/config.rb

@@ -11,6 +11,7 @@ class Config #:nodoc
       :parameterize_keys,
       :persist_in_safe_mode,
       :raise_not_found_error,
+      :autocreate_indexes,
       :use_object_ids,
       :skip_version_check
 
@@ -184,11 +185,17 @@ def reset
       @persist_in_safe_mode = true
       @raise_not_found_error = true
       @reconnect_time = 3
+      @autocreate_indexes = false
       @use_object_ids = false
       @skip_version_check = false
       @time_zone = nil
     end
 
+    # Allows the override of autocreate_indexes via ENV variable
+    def autocreate_indexes
+      ENV["MONGOID_CREATE_INDEXES"] || @autocreate_indexes
+    end
+
     ##
     # If Mongoid.use_object_ids = true
     #   Convert args to BSON::ObjectID

lib/mongoid/indexes.rb

@@ -11,16 +11,20 @@ module ClassMethods #:nodoc
       # Add the default indexes to the root document if they do not already
       # exist. Currently this is only _type.
       def add_indexes
-        if hereditary && !indexed
-          self._collection.create_index(:_type, :unique => false, :background => true)
-          self.indexed = true
+        if Mongoid.autocreate_indexes
+          if hereditary && !indexed
+            self._collection.create_index(:_type, :unique => false, :background => true)
+            self.indexed = true
+          end
         end
       end
 
       # Adds an index on the field specified. Options can be :unique => true or
       # :unique => false. It will default to the latter.
       def index(name, options = { :unique => false })
-        collection.create_index(name, options)
+        if Mongoid.autocreate_indexes
+          collection.create_index(name, options)
+        end
       end
     end
   end

lib/mongoid/railties/database.rake

@@ -54,6 +54,15 @@ namespace :db do
     end
   end
 
+  if not Rake::Task.task_defined?("db:create_indexes")
+    task :create_indexes do
+      # force mongoid to create indexes
+      ENV["MONGOID_CREATE_INDEXES"] = true
+      Rake::Task["environment"].invoke
+    end
+  end
+
+
   ########
   # TODO: lots more useful db tasks can be added here. stuff like copyDatabase, etc
   ########

spec/config/mongoid.yml

@@ -10,6 +10,7 @@ defaults: &defaults
   persist_in_safe_mode: false
   raise_not_found_error: false
   reconnect_time: 5
+  autocreate_indexes: false
   use_object_ids: true
   persist_types: false
   option_no_exist: false

spec/unit/mongoid/indexes_spec.rb

@@ -29,6 +29,8 @@
     context "when indexes have not been added" do
 
       before do
+        Mongoid.autocreate_indexes = true
+
         @class = Class.new do
           include Mongoid::Indexes
           def self.hereditary
@@ -37,6 +39,10 @@ def self.hereditary
         end
       end
 
+      after do
+        Mongoid.autocreate_indexes = false
+      end
+
       it "adds the _type index" do
         @class.expects(:_collection).returns(@collection)
         @collection.expects(:create_index).with(:_type, :unique => false, :background => true)
@@ -69,13 +75,19 @@ def self.hereditary
   describe ".index" do
 
     before do
+      Mongoid.autocreate_indexes = true
+
       @collection = mock
       @class = Class.new do
         include Mongoid::Indexes
       end
       @class.expects(:collection).returns(@collection)
     end
 
+    after do
+      Mongoid.autocreate_indexes = false
+    end
+
     context "when unique" do
 
       it "creates a unique index on the collection" do
@@ -86,6 +98,13 @@ def self.hereditary
     end
 
     context "when not unique" do
+      before do
+        Mongoid.autocreate_indexes = true
+      end
+
+      after do
+        Mongoid.autocreate_indexes = false
+      end
 
       it "creates an index on the collection" do
         @collection.expects(:create_index).with(:name, :unique => false)