Use the right type_map

activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb

@@ -142,7 +142,7 @@ def exec_query(sql, name = 'SQL', binds = [])
           fields.each_with_index do |fname, i|
             ftype = result.ftype i
             fmod  = result.fmod i
-            types[fname] = OID::TYPE_MAP.fetch(ftype, fmod) { |oid, mod|
+            types[fname] = type_map.fetch(ftype, fmod) { |oid, mod|
               warn "unknown OID: #{fname}(#{oid}) (#{sql})"
               OID::Identity.new
             }

activerecord/lib/active_record/connection_adapters/postgresql/oid.rb

@@ -301,11 +301,9 @@ def fetch(ftype, fmod)
           end
         end
 
-        TYPE_MAP = TypeMap.new # :nodoc:
-
-        # When the PG adapter connects, the pg_type table is queried.  The
+        # When the PG adapter connects, the pg_type table is queried. The
         # key of this hash maps to the `typname` column from the table.
-        # TYPE_MAP is then dynamically built with oids as the key and type
+        # type_map is then dynamically built with oids as the key and type
         # objects as values.
         NAMES = Hash.new { |h,k| # :nodoc:
           h[k] = OID::Identity.new