postgresql - How is compiled PL/pgSQL block? -

   $$   declare     tm1 timestamp without time zone;    tm2 timestamp without time zone;   begin      select localtimestamp(0) tm1;      in 1..200000000 loop         --just waiting several second      end loop;      select localtimestamp(0) tm2;        raise notice '% ; %', tm1, tm2;   end;   $$ language plpgsql 

why gives procedure same values tm1 , tm2 ?

is not executed code step step?

from manual

these sql-standard functions return values based on start time of current transaction [...] since these functions return start time of current transaction, values do not change during transaction. considered feature: intent allow single transaction have consistent notion of "current" time, multiple modifications within same transaction bear same time stamp

^{(emphasis mine)}

you want clock_timestamp()