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 5b95730e.

activerecord/CHANGELOG

 *Rails 3.0.0 [beta 4/release candidate] (unreleased)*
 
-* Add index length support for MySQL. #1852 [Emili Parreno, Pratik Naik]
-
-  Example:
-
-    add_index(:accounts, :name, :name => 'by_name', :length => 10)
-    => CREATE INDEX by_name ON accounts(name(10))
-
-    add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => {:name => 10, :surname => 15})
-    => CREATE INDEX by_name_surname ON accounts(name(10), surname(15))
-
 * find_or_create_by_attr(value, ...) works when attr is protected.  #4457 [Santiago Pastorino, Marc-André Lafortune]
 
 * New callbacks: after_commit and after_rollback. Do expensive operations like image thumbnailing after_commit instead of after_save.  #2991 [Brian Durand]

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -258,7 +258,7 @@ def simplified_type(field_type)
         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

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -256,32 +256,18 @@ def rename_column(table_name, column_name, new_column_name)
       # 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 @@ def add_index(table_name, column_name, options = {})
         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 @@ def remove_timestamps(table_name)
       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

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -461,11 +461,10 @@ def indexes(table_name, name = nil)#:nodoc:
           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 @@ def limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key)
       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)

activerecord/lib/active_record/schema_dumper.rb

@@ -177,7 +177,6 @@ def indexes(table, stream)
             statment_parts << index.columns.inspect
             statment_parts << (':name => ' + index.name.inspect)
             statment_parts << ':unique => true' if index.unique
-            statment_parts << (':length => ' + Hash[*index.columns.zip(index.lengths).flatten].inspect) if index.lengths.compact.present?
 
             '  ' + statment_parts.join(', ')
           end

activerecord/test/cases/active_schema_test_mysql.rb

@@ -15,23 +15,6 @@ def teardown
     end
   end
 
-  def test_add_index
-    expected = "CREATE  INDEX `index_people_on_last_name` ON `people` (`last_name`)"
-    assert_equal expected, add_index(:people, :last_name, :length => nil)
-
-    expected = "CREATE  INDEX `index_people_on_last_name` ON `people` (`last_name`(10))"
-    assert_equal expected, add_index(:people, :last_name, :length => 10)
-
-    expected = "CREATE  INDEX `index_people_on_last_name_and_first_name` ON `people` (`last_name`(15), `first_name`(15))"
-    assert_equal expected, add_index(:people, [:last_name, :first_name], :length => 15)
-
-    expected = "CREATE  INDEX `index_people_on_last_name_and_first_name` ON `people` (`last_name`(15), `first_name`)"
-    assert_equal expected, add_index(:people, [:last_name, :first_name], :length => {:last_name => 15})
-
-    expected = "CREATE  INDEX `index_people_on_last_name_and_first_name` ON `people` (`last_name`(15), `first_name`(10))"
-    assert_equal expected, add_index(:people, [:last_name, :first_name], :length => {:last_name => 15, :first_name => 10})
-  end
-
   def test_drop_table
     assert_equal "DROP TABLE `people`", drop_table(:people)
   end

activerecord/test/cases/migration_test.rb

@@ -92,14 +92,6 @@ def test_add_index
         assert_nothing_raised { Person.connection.remove_index("people", "last_name_and_first_name") }
         assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
         assert_nothing_raised { Person.connection.remove_index("people", ["last_name", "first_name"]) }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name"], :length => 10) }
-        assert_nothing_raised { Person.connection.remove_index("people", "last_name") }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name"], :length => {:last_name => 10}) }
-        assert_nothing_raised { Person.connection.remove_index("people", ["last_name"]) }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"], :length => 10) }
-        assert_nothing_raised { Person.connection.remove_index("people", ["last_name", "first_name"]) }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"], :length => {:last_name => 10, :first_name => 20}) }
-        assert_nothing_raised { Person.connection.remove_index("people", ["last_name", "first_name"]) }
       end
 
       # quoting