1 files changed, 36 insertions, 0 deletions
diff --git a/lib/gitlab/database/as_with_materialized.rb b/lib/gitlab/database/as_with_materialized.rb
new file mode 100644
index 00000000000..7c45f416638
--- /dev/null
+++ b/lib/gitlab/database/as_with_materialized.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    # This class is a special Arel node which allows optionally define the `MATERIALIZED` keyword for CTE and Recursive CTE queries.
+    class AsWithMaterialized < Arel::Nodes::Binary
+      extend Gitlab::Utils::StrongMemoize
+
+      MATERIALIZED = Arel.sql(' MATERIALIZED')
+      EMPTY_STRING = Arel.sql('')
+      attr_reader :expr
+
+      def initialize(left, right, materialized: true)
+        @expr = if materialized && self.class.materialized_supported?
+                  MATERIALIZED
+                else
+                  EMPTY_STRING
+                end
+
+        super(left, right)
+      end
+
+      # Note: to be deleted after the minimum PG version is set to 12.0
+      def self.materialized_supported?
+        strong_memoize(:materialized_supported) do
+          Gitlab::Database.version.match?(/^1[2-9]\./) # version 12.x and above
+        end
+      end
+
+      # Note: to be deleted after the minimum PG version is set to 12.0
+      def self.materialized_if_supported
+        materialized_supported? ? 'MATERIALIZED' : ''
+      end
+    end
+  end
+end