Merge pull request #35615 from kamipo/optimizer_hints

Support Optimizer Hints

9 files changed, 56 insertions, 2 deletions

diff --git a/activerecord/lib/arel/nodes/select_core.rb b/activerecord/lib/arel/nodes/select_core.rb
index 73461ff683..5814cae98a 100644
--- a/activerecord/lib/arel/nodes/select_core.rb
+++ b/activerecord/lib/arel/nodes/select_core.rb
@@ -4,7 +4,7 @@ module Arel # :nodoc: all
   module Nodes
     class SelectCore < Arel::Nodes::Node
       attr_accessor :projections, :wheres, :groups, :windows
-      attr_accessor :havings, :source, :set_quantifier
+      attr_accessor :havings, :source, :set_quantifier, :optimizer_hints
 
       def initialize
         super()
@@ -42,7 +42,7 @@ module Arel # :nodoc: all
 
       def hash
         [
-          @source, @set_quantifier, @projections,
+          @source, @set_quantifier, @projections, @optimizer_hints,
           @wheres, @groups, @havings, @windows
         ].hash
       end
@@ -51,6 +51,7 @@ module Arel # :nodoc: all
         self.class == other.class &&
           self.source == other.source &&
           self.set_quantifier == other.set_quantifier &&
+          self.optimizer_hints == other.optimizer_hints &&
           self.projections == other.projections &&
           self.wheres == other.wheres &&
           self.groups == other.groups &&
diff --git a/activerecord/lib/arel/nodes/unary.rb b/activerecord/lib/arel/nodes/unary.rb
index 00639304e4..6d1ac36b0e 100644
--- a/activerecord/lib/arel/nodes/unary.rb
+++ b/activerecord/lib/arel/nodes/unary.rb
@@ -35,6 +35,7 @@ module Arel # :nodoc: all
       Not
       Offset
       On
+      OptimizerHints
       Ordering
       RollUp
     }.each do |name|
diff --git a/activerecord/lib/arel/select_manager.rb b/activerecord/lib/arel/select_manager.rb
index 0da52ca91b..32286b67f4 100644
--- a/activerecord/lib/arel/select_manager.rb
+++ b/activerecord/lib/arel/select_manager.rb
@@ -146,6 +146,13 @@ module Arel # :nodoc: all
       @ctx.projections = projections
     end
 
+    def optimizer_hints(*hints)
+      unless hints.empty?
+        @ctx.optimizer_hints = Arel::Nodes::OptimizerHints.new(hints)
+      end
+      self
+    end
+
     def distinct(value = true)
       if value
         @ctx.set_quantifier = Arel::Nodes::Distinct.new
diff --git a/activerecord/lib/arel/visitors/depth_first.rb b/activerecord/lib/arel/visitors/depth_first.rb
index 92d309453c..892d670c79 100644
--- a/activerecord/lib/arel/visitors/depth_first.rb
+++ b/activerecord/lib/arel/visitors/depth_first.rb
@@ -35,6 +35,7 @@ module Arel # :nodoc: all
         alias :visit_Arel_Nodes_Ascending         :unary
         alias :visit_Arel_Nodes_Descending        :unary
         alias :visit_Arel_Nodes_UnqualifiedColumn :unary
+        alias :visit_Arel_Nodes_OptimizerHints    :unary
 
         def function(o)
           visit o.expressions
diff --git a/activerecord/lib/arel/visitors/dot.rb b/activerecord/lib/arel/visitors/dot.rb
index 6389c875cb..ffcbb7a7ab 100644
--- a/activerecord/lib/arel/visitors/dot.rb
+++ b/activerecord/lib/arel/visitors/dot.rb
@@ -82,6 +82,7 @@ module Arel # :nodoc: all
         alias :visit_Arel_Nodes_Offset            :unary
         alias :visit_Arel_Nodes_On                :unary
         alias :visit_Arel_Nodes_UnqualifiedColumn :unary
+        alias :visit_Arel_Nodes_OptimizerHints    :unary
         alias :visit_Arel_Nodes_Preceding         :unary
         alias :visit_Arel_Nodes_Following         :unary
         alias :visit_Arel_Nodes_Rows              :unary
diff --git a/activerecord/lib/arel/visitors/ibm_db.rb b/activerecord/lib/arel/visitors/ibm_db.rb
index 73166054da..0ffc0725f7 100644
--- a/activerecord/lib/arel/visitors/ibm_db.rb
+++ b/activerecord/lib/arel/visitors/ibm_db.rb
@@ -4,6 +4,14 @@ module Arel # :nodoc: all
   module Visitors
     class IBM_DB < Arel::Visitors::ToSql
       private
+        def visit_Arel_Nodes_SelectCore(o, collector)
+          collector = super
+          maybe_visit o.optimizer_hints, collector
+        end
+
+        def visit_Arel_Nodes_OptimizerHints(o, collector)
+          collector << "/* <OPTGUIDELINES>#{sanitize_as_sql_comment(o).join}</OPTGUIDELINES> */"
+        end
 
         def visit_Arel_Nodes_Limit(o, collector)
           collector << "FETCH FIRST "
@@ -16,6 +24,10 @@ module Arel # :nodoc: all
           collector = visit [o.left, o.right, 0, 1], collector
           collector << ")"
         end
+
+        def collect_optimizer_hints(o, collector)
+          collector
+        end
     end
   end
 end
diff --git a/activerecord/lib/arel/visitors/informix.rb b/activerecord/lib/arel/visitors/informix.rb
index 208fa15aef..cd43be8858 100644
--- a/activerecord/lib/arel/visitors/informix.rb
+++ b/activerecord/lib/arel/visitors/informix.rb
@@ -42,10 +42,15 @@ module Arel # :nodoc: all
           collector
         end
 
+        def visit_Arel_Nodes_OptimizerHints(o, collector)
+          collector << "/*+ #{sanitize_as_sql_comment(o).join(", ")} */"
+        end
+
         def visit_Arel_Nodes_Offset(o, collector)
           collector << "SKIP "
           visit o.expr, collector
         end
+
         def visit_Arel_Nodes_Limit(o, collector)
           collector << "FIRST "
           visit o.expr, collector
diff --git a/activerecord/lib/arel/visitors/mssql.rb b/activerecord/lib/arel/visitors/mssql.rb
index fdd864b40d..85815baca2 100644
--- a/activerecord/lib/arel/visitors/mssql.rb
+++ b/activerecord/lib/arel/visitors/mssql.rb
@@ -76,6 +76,15 @@ module Arel # :nodoc: all
           end
         end
 
+        def visit_Arel_Nodes_SelectCore(o, collector)
+          collector = super
+          maybe_visit o.optimizer_hints, collector
+        end
+
+        def visit_Arel_Nodes_OptimizerHints(o, collector)
+          collector << "OPTION (#{sanitize_as_sql_comment(o).join(", ")})"
+        end
+
         def get_offset_limit_clause(o)
           first_row = o.offset ? o.offset.expr.to_i + 1 : 1
           last_row  = o.limit ? o.limit.expr.to_i - 1 + first_row : nil
@@ -103,6 +112,10 @@ module Arel # :nodoc: all
           end
         end
 
+        def collect_optimizer_hints(o, collector)
+          collector
+        end
+
         def determine_order_by(orders, x)
           if orders.any?
             orders
diff --git a/activerecord/lib/arel/visitors/to_sql.rb b/activerecord/lib/arel/visitors/to_sql.rb
index d0dec63860..7e3e265208 100644
--- a/activerecord/lib/arel/visitors/to_sql.rb
+++ b/activerecord/lib/arel/visitors/to_sql.rb
@@ -219,6 +219,7 @@ module Arel # :nodoc: all
         def visit_Arel_Nodes_SelectCore(o, collector)
           collector << "SELECT"
 
+          collector = collect_optimizer_hints(o, collector)
           collector = maybe_visit o.set_quantifier, collector
 
           collect_nodes_for o.projections, collector, SPACE
@@ -236,6 +237,10 @@ module Arel # :nodoc: all
           collector
         end
 
+        def visit_Arel_Nodes_OptimizerHints(o, collector)
+          collector << "/*+ #{sanitize_as_sql_comment(o).join(" ")} */"
+        end
+
         def collect_nodes_for(nodes, collector, spacer, connector = COMMA)
           unless nodes.empty?
             collector << spacer
@@ -799,6 +804,14 @@ module Arel # :nodoc: all
           @connection.quote_column_name(name)
         end
 
+        def sanitize_as_sql_comment(o)
+          o.expr.map { |v| v.gsub(%r{ /\*\+?\s* | \s*\*/ }x, "") }
+        end
+
+        def collect_optimizer_hints(o, collector)
+          maybe_visit o.optimizer_hints, collector
+        end
+
         def maybe_visit(thing, collector)
           return collector unless thing
           collector << " "