rails-4.1-postgres-opclass.patch

diff -ur activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
--- activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb	2014-07-11 02:35:32.000000000 +0200
+++ activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb	2014-07-11 01:31:14.000000000 +0200
@@ -8,7 +8,7 @@
     # Abstract representation of an index definition on a table. Instances of
     # this type are typically created and returned by methods in database
     # adapters. e.g. ActiveRecord::ConnectionAdapters::AbstractMysqlAdapter#indexes
-    class IndexDefinition < Struct.new(:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using) #:nodoc:
+    class IndexDefinition < Struct.new(:table, :name, :unique, :columns, :lengths, :orders, :where, :type, :using, :opclass) #:nodoc:
     end
 
     # Abstract representation of a column definition. Instances of this type
diff -ur activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
--- activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb	2014-07-11 02:35:32.000000000 +0200
+++ activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb	2014-07-11 02:25:23.000000000 +0200
@@ -774,7 +774,7 @@
           column_names = Array(column_name)
           index_name   = index_name(table_name, column: column_names)
 
-          options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type)
+          options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type, :opclass)
 
           index_type = options[:unique] ? "UNIQUE" : ""
           index_type = options[:type].to_s if options.key?(:type)
@@ -788,6 +788,7 @@
           end
 
           using = "USING #{options[:using]}" if options[:using].present?
+          opclass = " #{options[:opclass]}" if options[:using].present? && options[:opclass].present?
 
           if supports_partial_index?
             index_options = options[:where] ? " WHERE #{options[:where]}" : ""
@@ -801,7 +802,7 @@
           end
           index_columns = quoted_columns_for_index(column_names, options).join(", ")
 
-          [index_name, index_type, index_columns, index_options, algorithm, using]
+          [index_name, index_type, index_columns, index_options, algorithm, using, opclass]
         end
 
         def index_name_for_remove(table_name, options = {})
diff -ur activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
--- activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb	2014-07-11 02:35:32.000000000 +0200
+++ activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb	2014-07-11 02:22:27.000000000 +0200
@@ -153,6 +153,8 @@
             ORDER BY i.relname
           SQL
 
+          valid_opclasses = Regexp.union(opclasses) if result.any?
+
           result.map do |row|
             index_name = row[0]
             unique = row[1] == 't'
@@ -175,12 +177,21 @@
               orders = desc_order_columns.any? ? Hash[desc_order_columns.map {|order_column| [order_column, :desc]}] : {}
               where = inddef.scan(/WHERE (.+)$/).flatten[0]
               using = inddef.scan(/USING (.+?) /).flatten[0].to_sym
+              opclass = inddef.scan(/USING .+? \(.+? (#{valid_opclasses.source})\)/).flatten[0].try(:to_sym)
 
-              IndexDefinition.new(table_name, index_name, unique, column_names, [], orders, where, nil, using)
+              IndexDefinition.new(table_name, index_name, unique, column_names, [], orders, where, nil, using, opclass)
             end
           end.compact
         end
 
+        # Returns the list of all avalable index opclasses.
+        def opclasses
+          query(<<-SQL, 'SCHEMA').map { |row| row[0] }
+            SELECT opcname
+            FROM pg_opclass
+          SQL
+        end
+
         # Returns the list of all column definitions for a table.
         def columns(table_name)
           # Limit, precision, and scale are all handled by the superclass.
@@ -432,8 +443,8 @@
         end
 
         def add_index(table_name, column_name, options = {}) #:nodoc:
-          index_name, index_type, index_columns, index_options, index_algorithm, index_using = add_index_options(table_name, column_name, options)
-          execute "CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns})#{index_options}"
+          index_name, index_type, index_columns, index_options, index_algorithm, index_using, index_opclass = add_index_options(table_name, column_name, options)
+          execute "CREATE #{index_type} INDEX #{index_algorithm} #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} #{index_using} (#{index_columns}#{index_opclass})#{index_options}"
         end
 
         def remove_index!(table_name, index_name) #:nodoc:
diff -ur activerecord/lib/active_record/schema_dumper.rb activerecord/lib/active_record/schema_dumper.rb
--- activerecord/lib/active_record/schema_dumper.rb	2014-07-11 02:35:32.000000000 +0200
+++ activerecord/lib/active_record/schema_dumper.rb	2014-07-11 02:10:11.000000000 +0200
@@ -202,6 +202,8 @@
 
             statement_parts << ('using: ' + index.using.inspect) if index.using
 
+            statement_parts << ('opclass: ' + index.opclass.inspect) if index.opclass
+
             statement_parts << ('type: ' + index.type.inspect) if index.type
 
             '  ' + statement_parts.join(', ')

These are the minimum required changes to get postgresql index opclass support for migrations and schema dumping. This was supported up to postgres_ext 1.0 with Rails 3.2 with the option index_opclass, but has been removed from the rail 4 versions of the gem.

The patch was created against rails/activerecord 4.1.4.