revert changes

lib/arel/visitors/oracle12_hack.rb

@@ -23,6 +23,37 @@ def visit_Arel_Nodes_NotIn(o, collector)
         super
       end
 
+      # Another wonderful piece.
+      # Oracle can't compare CLOB columns with standard SQL operators for comparison.
+      # We need to replace standard equality for text/binary columns to use DBMS_LOB.COMPARE function.
+      # Fixes ORA-00932: inconsistent datatypes: expected - got CLOB
+      # remove if https://github.com/rsim/oracle-enhanced/issues/2239 is fixed (in Rails 7.0.1)
+      def visit_Arel_Nodes_Equality(o, collector)
+        case (left = o.left)
+        when Arel::Attributes::Attribute
+          table = left.relation.table_name
+          schema_cache = @connection.schema_cache
+
+          return super unless schema_cache.columns_hash?(table)
+
+          column = schema_cache.columns_hash(table)[left.name.to_s]
+
+          case column.type
+          when :text, :binary
+            # https://docs.oracle.com/cd/B19306_01/appdev.102/b14258/d_lob.htm#i1016668
+            # returns 0 when the comparison succeeds
+            comparator = Arel::Nodes::NamedFunction.new('DBMS_LOB.COMPARE', [left, o.right])
+            collector = visit comparator, collector
+            collector << ' = 0'
+            collector
+          else
+            super
+          end
+        else
+          super
+        end
+      end
+
       # remove when addressed: https://github.com/rsim/oracle-enhanced/pull/2247 - included in v7.1.0
       def visit_Arel_Nodes_Matches o, collector
         if !o.case_sensitive && o.left && o.right