Use bulk INSERT to insert fixtures

Improves the performance from O(n) to O(1).
Previously it would require 50 queries to
insert 50 fixtures. Now it takes only one query.

Disabled on sqlite which doesn't support multiple inserts.

9 files changed, 117 insertions, 11 deletions

diff --git a/Gemfile.lock b/Gemfile.lock
index 7586cdee56..9f636b0307 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -17,7 +17,7 @@ GIT
 
 GIT
   remote: https://github.com/rails/arel.git
-  revision: 5db56a513286814991c27000af2c0243cc19d1e2
+  revision: 67a51c62f4e19390cd8eb408596ca48bb0806362
   specs:
     arel (8.0.0)
 
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index f75f1a9108..c65deffa8b 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Use bulk INSERT to insert fixtures for better performance.
+
+    *Kir Shatrov*
+
 *   Prevent making bind param if casted value is nil.
 
     *Ryuta Kamizono*
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index 56f0d6d1f4..dc766ce4fc 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -296,6 +296,9 @@ module ActiveRecord
 
       # Inserts the given fixture into the table. Overridden in adapters that require
       # something beyond a simple insert (eg. Oracle).
+      # Most of adapters should implement `insert_fixtures` that leverages bulk SQL insert.
+      # We keep this method to provide fallback
+      # for databases like sqlite that do not support bulk inserts.
       def insert_fixture(fixture, table_name)
         fixture = fixture.stringify_keys
 
@@ -312,12 +315,7 @@ module ActiveRecord
         table = Arel::Table.new(table_name)
 
         values = binds.map do |bind|
-          value = bind.value_for_database
-          begin
-            quote(value)
-          rescue TypeError
-            value = YAML.dump(value)
-          end
+          value = with_yaml_fallback(bind.value_for_database)
           [table[bind.name], value]
         end
 
@@ -327,6 +325,40 @@ module ActiveRecord
         execute manager.to_sql, "Fixture Insert"
       end
 
+      # Inserts a set of fixtures into the table. Overridden in adapters that require
+      # something beyond a simple insert (eg. Oracle).
+      def insert_fixtures(fixtures, table_name)
+        return if fixtures.empty?
+
+        columns = schema_cache.columns_hash(table_name)
+
+        values = fixtures.map do |fixture|
+          fixture = fixture.stringify_keys
+
+          unknown_columns = fixture.keys - columns.keys
+          if unknown_columns.any?
+            raise Fixture::FixtureError, %(table "#{table_name}" has no columns named #{unknown_columns.map(&:inspect).join(', ')}.)
+          end
+
+          columns.map do |name, column|
+            if fixture.key?(name)
+              type = lookup_cast_type_from_column(column)
+              bind = Relation::QueryAttribute.new(name, fixture[name], type)
+              with_yaml_fallback(bind.value_for_database)
+            else
+              Arel.sql("DEFAULT")
+            end
+          end
+        end
+
+        table = Arel::Table.new(table_name)
+        manager = Arel::InsertManager.new
+        manager.into(table)
+        columns.each_key { |column| manager.columns << table[column] }
+        manager.values = manager.create_values_list(values)
+        execute manager.to_sql, "Fixtures Insert"
+      end
+
       def empty_insert_statement_value
         "DEFAULT VALUES"
       end
@@ -388,6 +420,18 @@ module ActiveRecord
           end
           [relation, binds]
         end
+
+        # Fixture value is quoted by Arel, however scalar values
+        # are not quotable. In this case we want to convert
+        # the column value to YAML.
+        def with_yaml_fallback(value)
+          begin
+            quote(value)
+          rescue TypeError
+            value = YAML.dump(value)
+          end
+          value
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 648c869915..c42e80ea2c 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -526,8 +526,25 @@ module ActiveRecord
         index.using == :btree || super
       end
 
+      def insert_fixtures(*)
+        without_sql_mode("NO_AUTO_VALUE_ON_ZERO") { super }
+      end
+
       private
 
+        def without_sql_mode(mode)
+          result = execute("SELECT @@SESSION.sql_mode")
+          current_mode = result.first[0]
+          return yield unless current_mode.include?(mode)
+
+          sql_mode = "REPLACE(@@sql_mode, '#{mode}', '')"
+          execute("SET @@SESSION.sql_mode = #{sql_mode}")
+          yield
+        ensure
+          sql_mode = "CONCAT(@@sql_mode, ',#{mode}')"
+          execute("SET @@SESSION.sql_mode = #{sql_mode}")
+        end
+
         def initialize_type_map(m)
           super
 
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 7233325d5a..ee2faf43b5 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -349,6 +349,12 @@ module ActiveRecord
         end
       end
 
+      def insert_fixtures(rows, table_name)
+        rows.each do |row|
+          insert_fixture(row, table_name)
+        end
+      end
+
       private
 
         def table_structure(table_name)
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index a6b66c91e3..e9acb8acae 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -567,9 +567,7 @@ module ActiveRecord
               end
 
               table_rows.each do |fixture_set_name, rows|
-                rows.each do |row|
-                  conn.insert_fixture(row, fixture_set_name)
-                end
+                conn.insert_fixtures(rows, fixture_set_name)
               end
 
               # Cap primary key sequences to max(pk).
diff --git a/activerecord/test/cases/adapters/postgresql/array_test.rb b/activerecord/test/cases/adapters/postgresql/array_test.rb
index c78c6178ff..121c62dadf 100644
--- a/activerecord/test/cases/adapters/postgresql/array_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/array_test.rb
@@ -191,6 +191,12 @@ class PostgresqlArrayTest < ActiveRecord::PostgreSQLTestCase
     assert_equal(PgArray.last.tags, tag_values)
   end
 
+  def test_insert_fixtures
+    tag_values = ["val1", "val2", "val3_with_'_multiple_quote_'_chars"]
+    @connection.insert_fixtures([{ "tags" => tag_values }], "pg_arrays")
+    assert_equal(PgArray.last.tags, tag_values)
+  end
+
   def test_attribute_for_inspect_for_array_field
     record = PgArray.new { |a| a.ratings = (1..10).to_a }
     assert_equal("[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]", record.attribute_for_inspect(:ratings))
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index a0a6d3c7ef..b499e60922 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -54,6 +54,31 @@ class FixturesTest < ActiveRecord::TestCase
     end
   end
 
+  class InsertQuerySubscriber
+    attr_reader :events
+
+    def initialize
+      @events = []
+    end
+
+    def call(_, _, _, _, values)
+      @events << values[:sql] if values[:sql] =~ /INSERT/
+    end
+  end
+
+  if current_adapter?(:Mysql2Adapter, :PostgreSQLAdapter)
+    def test_bulk_insert
+      begin
+        subscriber = InsertQuerySubscriber.new
+        subscription = ActiveSupport::Notifications.subscribe("sql.active_record", subscriber)
+        create_fixtures("bulbs")
+        assert_equal 1, subscriber.events.size, "It takes one INSERT query to insert two fixtures"
+      ensure
+        ActiveSupport::Notifications.unsubscribe(subscription)
+      end
+    end
+  end
+
   def test_broken_yaml_exception
     badyaml = Tempfile.new ["foo", ".yml"]
     badyaml.write "a: : "
@@ -248,7 +273,12 @@ class FixturesTest < ActiveRecord::TestCase
     e = assert_raise(ActiveRecord::Fixture::FixtureError) do
       ActiveRecord::FixtureSet.create_fixtures(FIXTURES_ROOT + "/naked/yml", "parrots")
     end
-    assert_equal(%(table "parrots" has no column named "arrr".), e.message)
+
+    if current_adapter?(:SQLite3Adapter)
+      assert_equal(%(table "parrots" has no column named "arrr".), e.message)
+    else
+      assert_equal(%(table "parrots" has no columns named "arrr", "foobar".), e.message)
+    end
   end
 
   def test_yaml_file_with_symbol_columns
diff --git a/activerecord/test/fixtures/naked/yml/parrots.yml b/activerecord/test/fixtures/naked/yml/parrots.yml
index 3e10331105..76f66e01ae 100644
--- a/activerecord/test/fixtures/naked/yml/parrots.yml
+++ b/activerecord/test/fixtures/naked/yml/parrots.yml
@@ -1,2 +1,3 @@
 george:
   arrr: "Curious George"
+  foobar: Foobar