Andrew Perrin <andrew_perrin@unc.edu> writes:
> Except that he wants max(timestamp) by id; perhaps a GROUP BY would
> help, something like (untested):
Oh, I'm sorry, I missed the "for each id" bit.
> select max(timestamp) from log group by id;
That gives you the max timestamp for each id, all right, but not the
rest of the row in which the max timestamp occurs. I know of no good
way to get that in standard SQL. If you don't mind being nonstandard,
this is exactly the problem SELECT DISTINCT ON is meant for:
select distinct on (id) * from log order by id, timestamp desc;
See the SELECT reference page for more about this.
regards, tom lane