Support `columns_for_distinct`

2 files changed, 4 insertions, 3 deletions

diff --git a/lib/arel/visitors/oracle.rb b/lib/arel/visitors/oracle.rb
index b58d7338ef..b6f7b4cc3c 100644
--- a/lib/arel/visitors/oracle.rb
+++ b/lib/arel/visitors/oracle.rb
@@ -8,7 +8,7 @@ module Arel
 
         # if need to select first records without ORDER BY and GROUP BY and without DISTINCT
         # then can use simple ROWNUM in WHERE clause
-        if o.limit && o.orders.empty? && !o.offset && o.cores.first.projections.first !~ /^DISTINCT /
+        if o.limit && o.orders.empty? && !o.offset && o.cores.first.set_quantifier.class.to_s !~ /Distinct/
           o.cores.last.wheres.push Nodes::LessThanOrEqual.new(
             Nodes::SqlLiteral.new('ROWNUM'), o.limit.expr
           )
@@ -83,7 +83,7 @@ module Arel
         return o if o.orders.empty?
         return o unless o.cores.any? do |core|
           core.projections.any? do |projection|
-            /DISTINCT.*FIRST_VALUE/ === projection
+            /FIRST_VALUE/ === projection
           end
         end
         # Previous version with join and split broke ORDER BY clause
diff --git a/test/visitors/test_oracle.rb b/test/visitors/test_oracle.rb
index 421e9951e6..bd22822bca 100644
--- a/test/visitors/test_oracle.rb
+++ b/test/visitors/test_oracle.rb
@@ -85,7 +85,8 @@ module Arel
 
           it 'creates a subquery when there is DISTINCT' do
             stmt = Nodes::SelectStatement.new
-            stmt.cores.first.projections << Nodes::SqlLiteral.new('DISTINCT id')
+            stmt.cores.first.set_quantifier = Arel::Nodes::Distinct.new
+            stmt.cores.first.projections << Nodes::SqlLiteral.new('id')
             stmt.limit = Arel::Nodes::Limit.new(10)
             sql = @visitor.accept stmt
             sql.must_be_like %{