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 f72d2974c89457743312dc2bc73efa55a83a91b6..18dc73337be5836f50a9fb77e869e5798cf6eb80 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -127,6 +127,7 @@ def initialize(connection, logger, connection_options, config)
         super(connection, logger)
         @connection_options, @config = connection_options, config
         @quoted_column_names, @quoted_table_names = {}, {}
+        @visitor = Arel::Visitors::MySQL.new self
       end
 
       def self.visitor_for(pool) # :nodoc:
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index b7918c7f07538f21230f55777138f9173de231f2..d98cf5051febe1bcec3991b333bbfe08b6f7dfaa 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -307,6 +307,7 @@ def connection_active?
       def initialize(connection, logger, connection_parameters, config)
         super(connection, logger)
         @connection_parameters, @config = connection_parameters, config
+        @visitor = Arel::Visitors::PostgreSQL.new self
 
         # @local_tz is initialized as nil to avoid warnings when connect tries to use it
         @local_tz = nil