Merge pull request rails#14480 from steverice/mysql-indexes-in-create-table

Create indexes inline in CREATE TABLE for MySQL

Author: rafaelfranca

activerecord/CHANGELOG.md

@@ -1,3 +1,18 @@
+*   Create indexes inline in CREATE TABLE for MySQL
+
+    This is important, because adding an index on a temporary table after it has been created
+    would commit the transaction.
+    It also allows creating and dropping indexed tables with fewer queries and fewer permissions required.
+
+    Example:
+
+        create_table :temp, temporary: true, as: "SELECT id, name, zip FROM a_really_complicated_query" do |t|
+          t.index :zip
+        end
+        # => CREATE TEMPORARY TABLE temp (INDEX (zip)) AS SELECT id, name, zip FROM a_really_complicated_query
+
+    *Cody Cutrer*, *Steve Rice*
+
 *   Save `has_one` association even if the record doesn't changed.
 
     Fixes #14407.

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

@@ -186,24 +186,23 @@ def column_exists?(table_name, column_name, type = nil, options = {})
       def create_table(table_name, options = {})
         td = create_table_definition table_name, options[:temporary], options[:options], options[:as]
 
-        if !options[:as]
-          unless options[:id] == false
-            pk = options.fetch(:primary_key) {
-              Base.get_primary_key table_name.to_s.singularize
-            }
-
-            td.primary_key pk, options.fetch(:id, :primary_key), options
-          end
+        unless options[:id] == false || options[:as]
+          pk = options.fetch(:primary_key) {
+            Base.get_primary_key table_name.to_s.singularize
+          }
 
-          yield td if block_given?
+          td.primary_key pk, options.fetch(:id, :primary_key), options
         end
 
+        yield td if block_given?
+
         if options[:force] && table_exists?(table_name)
           drop_table(table_name, options)
         end
 
-        execute schema_creation.accept td
-        td.indexes.each_pair { |c,o| add_index table_name, c, o }
+        result = execute schema_creation.accept td
+        td.indexes.each_pair { |c,o| add_index table_name, c, o } unless supports_indexes_in_create?
+        result
       end
 
       # Creates a new join table with the name created using the lexical order of the first two
@@ -796,7 +795,7 @@ def add_index_options(table_name, column_name, options = {})
           if index_name.length > max_index_length
             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{max_index_length} characters"
           end
-          if index_name_exists?(table_name, index_name, false)
+          if table_exists?(table_name) && index_name_exists?(table_name, index_name, false)
             raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
           end
           index_columns = quoted_columns_for_index(column_names, options).join(", ")

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -217,6 +217,12 @@ def supports_extensions?
         false
       end
 
+      # Does this adapter support creating indexes in the same statement as
+      # creating the table? As of this writing, only mysql does.
+      def supports_indexes_in_create?
+        false
+      end
+
       # This is meant to be implemented by the adapters that support extensions
       def disable_extension(name)
       end

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -6,6 +6,17 @@ class AbstractMysqlAdapter < AbstractAdapter
       include Savepoints
 
       class SchemaCreation < AbstractAdapter::SchemaCreation
+        def visit_TableDefinition(o)
+          create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE "
+          create_sql << "#{quote_table_name(o.name)} "
+          statements = []
+          statements.concat(o.columns.map { |c| accept c })
+          statements.concat(o.indexes.map { |(column_name, options)| index_in_create(o.name, column_name, options) })
+          create_sql << "(#{statements.join(', ')}) " if statements.present?
+          create_sql << "#{o.options}"
+          create_sql << " AS #{@conn.to_sql(o.as)}" if o.as
+          create_sql
+        end
 
         def visit_AddColumn(o)
           add_column_position!(super, column_options(o))
@@ -29,6 +40,11 @@ def add_column_position!(sql, options)
           end
           sql
         end
+
+        def index_in_create(table_name, column_name, options)
+          index_name, index_type, index_columns, index_options, index_algorithm, index_using = @conn.send(:add_index_options, table_name, column_name, options)
+          "#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})#{index_options} #{index_algorithm}".gsub('  ', ' ').strip
+        end
       end
 
       def schema_creation
@@ -225,6 +241,10 @@ def supports_transaction_isolation?
         version[0] >= 5
       end
 
+      def supports_indexes_in_create?
+        true
+      end
+
       def native_database_types
         NATIVE_DATABASE_TYPES
       end

activerecord/test/cases/adapters/mysql/active_schema_test.rb

@@ -17,7 +17,8 @@ def execute(sql, name = nil) return sql end
   end
 
   def test_add_index
-    # add_index calls index_name_exists? which can't work since execute is stubbed
+    # add_index calls table_exists? and index_name_exists? which can't work since execute is stubbed
+    def (ActiveRecord::Base.connection).table_exists?(*); true; end
     def (ActiveRecord::Base.connection).index_name_exists?(*); false; end
 
     expected = "CREATE  INDEX `index_people_on_last_name`  ON `people` (`last_name`) "
@@ -116,6 +117,18 @@ def test_remove_timestamps
     end
   end
 
+  def test_indexes_in_create
+    begin
+      ActiveRecord::Base.connection.stubs(:table_exists?).with(:temp).returns(false)
+      ActiveRecord::Base.connection.stubs(:index_name_exists?).with(:index_temp_on_zip).returns(false)
+      expected = "CREATE TEMPORARY TABLE `temp` (INDEX `index_temp_on_zip` (`zip`)) ENGINE=InnoDB AS SELECT id, name, zip FROM a_really_complicated_query"
+      actual = ActiveRecord::Base.connection.create_table(:temp, temporary: true, as: "SELECT id, name, zip FROM a_really_complicated_query") do |t|
+        t.index :zip
+      end
+      assert_equal expected, actual
+    end
+  end
+
   private
     def with_real_execute
       ActiveRecord::Base.connection.singleton_class.class_eval do

activerecord/test/cases/adapters/mysql2/active_schema_test.rb

@@ -17,7 +17,8 @@ def execute(sql, name = nil) return sql end
   end
 
   def test_add_index
-    # add_index calls index_name_exists? which can't work since execute is stubbed
+    # add_index calls table_exists? and index_name_exists? which can't work since execute is stubbed
+    def (ActiveRecord::Base.connection).table_exists?(*); true; end
     def (ActiveRecord::Base.connection).index_name_exists?(*); false; end
 
     expected = "CREATE  INDEX `index_people_on_last_name`  ON `people` (`last_name`) "
@@ -116,6 +117,18 @@ def test_remove_timestamps
     end
   end
 
+  def test_indexes_in_create
+    begin
+      ActiveRecord::Base.connection.stubs(:table_exists?).with(:temp).returns(false)
+      ActiveRecord::Base.connection.stubs(:index_name_exists?).with(:index_temp_on_zip).returns(false)
+      expected = "CREATE TEMPORARY TABLE `temp` (INDEX `index_temp_on_zip` (`zip`)) ENGINE=InnoDB AS SELECT id, name, zip FROM a_really_complicated_query"
+      actual = ActiveRecord::Base.connection.create_table(:temp, temporary: true, as: "SELECT id, name, zip FROM a_really_complicated_query") do |t|
+        t.index :zip
+      end
+      assert_equal expected, actual
+    end
+  end
+
   private
     def with_real_execute
       ActiveRecord::Base.connection.singleton_class.class_eval do