added timestamp code, support columns for group by and order by and tested load has-many eager code

backends/postgres/test/CMakeLists.txt

@@ -31,6 +31,8 @@ set(TEST_SOURCES
   ../../../test/backends/StatementCacheTest.cpp
   ../../../test/backends/StatementTest.cpp
   ../../../test/backends/TypeTraitsTest.cpp
+  ../../../test/utils/record_printer.hpp
+  ../../../test/utils/record_printer.cpp
 )
 
 set(LIBRARY_TEST_TARGET PostgresTests)