create trigger tg1 after update on table1 for each row
execute procedure f1();

create or replace function f1() returns trigger as '
begin
execute ''insert into table2 select ''||quote_literal(''update table1 set field1='')||''||''||quote_literal(new.field1)||'', localtimestamp'';
return new;
end;' language plpgsql;

create or replace function f1() returns trigger as '
begin
insert into table2 select ''update table1 set field1=''||new.field1, localtimestamp;
return new;
end;' language plpgsql;