Обсуждение:

> might it be possible that "id" is not type integer/int4, e.g. numeric or
int8?
>
> try this query:
> rs2.executeUpdate("UPDATE my_table SET my_date=now() WHERE id='"+i+"'");

Yes !
you've got it... Now, postgres uses "Index Scan".

"id" is an int8. I didn't knew that it has to be quoted in order to be
interpreted into something else than an int4.


Thanks to everybody.

--
Xavier Bugaud

>
> "id" is an int8. I didn't knew that it has to be quoted in order to be
> interpreted into something else than an int4.

IMO it's a good idea to quote all numerics regardless of type in postgres. as a side effect, it will allow the planer
tomake smarter choices for int8.