Revert "Add index length support for MySQL [#1852 state:open]"

This commit breaks dumping a few tables, as the sessions table.
To reproduce, just create a new application and:

  rake db:sessions:create
  rake db:migrate
  rake db:test:prepare

And then look at the db/schema.rb file (ht: Sam Ruby).

This reverts commit 5b95730edc33ee97f53da26a3868eb983305a771.

3 files changed, 3 insertions, 37 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index e42cd99786..6c477e48ce 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -258,7 +258,7 @@ module ActiveRecord
         end
     end
 
-    class IndexDefinition < Struct.new(:table, :name, :unique, :columns, :lengths) #:nodoc:
+    class IndexDefinition < Struct.new(:table, :name, :unique, :columns) #:nodoc:
     end
 
     # Abstract representation of a column definition. Instances of this type
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 1255ef09be..e8cba1bd41 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -256,32 +256,18 @@ module ActiveRecord
       # name.
       #
       # ===== Examples
-      #
       # ====== Creating a simple index
       #  add_index(:suppliers, :name)
       # generates
       #  CREATE INDEX suppliers_name_index ON suppliers(name)
-      #
       # ====== Creating a unique index
       #  add_index(:accounts, [:branch_id, :party_id], :unique => true)
       # generates
       #  CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)
-      #
       # ====== Creating a named index
       #  add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')
       # generates
       #  CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)
-      #
-      # ====== Creating an index with specific key length
-      #  add_index(:accounts, :name, :name => 'by_name', :length => 10)
-      # generates
-      #  CREATE INDEX by_name ON accounts(name(10))
-      #
-      #  add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => {:name => 10, :surname => 15})
-      # generates
-      #  CREATE INDEX by_name_surname ON accounts(name(10), surname(15))
-      #
-      # Note: SQLite doesn't support index length
       def add_index(table_name, column_name, options = {})
         column_names = Array.wrap(column_name)
         index_name   = index_name(table_name, :column => column_names)
@@ -292,9 +278,7 @@ module ActiveRecord
         else
           index_type = options
         end
-
-        quoted_column_names = quoted_columns_for_index(column_names, options).join(", ")
-
+        quoted_column_names = column_names.map { |e| quote_column_name(e) }.join(", ")
         execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{quoted_column_names})"
       end
 
@@ -446,11 +430,6 @@ module ActiveRecord
       end
 
       protected
-        # Overridden by the mysql adapter for supporting index lengths
-        def quoted_columns_for_index(column_names, options = {})
-          column_names.map {|name| quote_column_name(name) }
-        end
-
         def options_include_default?(options)
           options.include?(:default) && !(options[:null] == false && options[:default].nil?)
         end
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 470ff8d767..55d9d20bb5 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -461,11 +461,10 @@ module ActiveRecord
           if current_index != row[2]
             next if row[2] == "PRIMARY" # skip the primary key
             current_index = row[2]
-            indexes << IndexDefinition.new(row[0], row[2], row[1] == "0", [], [])
+            indexes << IndexDefinition.new(row[0], row[2], row[1] == "0", [])
           end
 
           indexes.last.columns << row[4]
-          indexes.last.lengths << row[7]
         end
         result.free
         indexes
@@ -595,18 +594,6 @@ module ActiveRecord
       end
 
       protected
-        def quoted_columns_for_index(column_names, options = {})
-          length = options[:length] if options.is_a?(Hash)
-
-          quoted_column_names = case length
-          when Hash
-            column_names.map {|name| length[name] ? "#{quote_column_name(name)}(#{length[name]})" : quote_column_name(name) }
-          when Fixnum
-            column_names.map {|name| "#{quote_column_name(name)}(#{length})"}
-          else
-            column_names.map {|name| quote_column_name(name) }
-          end
-        end
 
         def translate_exception(exception, message)
           return super unless exception.respond_to?(:errno)