1 files changed, 15 insertions, 7 deletions
diff --git a/lib/arel/tree_manager.rb b/lib/arel/tree_manager.rb
index 11d34ec138..4ee4a6f219 100644
--- a/lib/arel/tree_manager.rb
+++ b/lib/arel/tree_manager.rb
@@ -4,23 +4,31 @@ module Arel
     include Arel::Relation
 
     VISITORS = {
-      'postgresql' => Arel::Visitors::PostgreSQL
+      'postgresql' => Arel::Visitors::PostgreSQL,
+      'mysql'      => Arel::Visitors::MySQL,
+      'mysql2'     => Arel::Visitors::MySQL,
     }
 
+    attr_accessor :visitor
+
     def initialize engine
-      @engine        = engine
-      @pool          = engine.connection_pool
-      @adapter       = @pool.spec.config[:adapter]
-      @visitor_klass = VISITORS[@adapter] || Visitors::ToSql
+      @engine  = engine
+      @visitor = nil
     end
 
     def to_dot
       Visitors::Dot.new.accept @head
     end
 
+    def visitor
+      return @visitor if @visitor
+      pool          = @engine.connection_pool
+      adapter       = pool.spec.config[:adapter]
+      @visitor = (VISITORS[adapter] || Visitors::ToSql).new(@engine)
+    end
+
     def to_sql
-      viz = @visitor_klass.new @engine
-      viz.accept @head
+      visitor.accept @head
     end
 
     def initialize_copy other