Magnus Hagander <magnus@hagander.net> writes:
> On Mon, Aug 23, 2010 at 16:38, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Magnus Hagander <magnus@hagander.net> writes:
>>> We could also store last_autovacuum_vacuum_duration - is that better
>>> or worse than start and end time?
>>
>> No, I think you want to know the actual time not only the duration.
> Well, you could calculate one from the other - especially if one takes
> less size, per your comment above.
With alignment considerations, adding a field is going to cost 8 bytes;
whether it's a timestamp or a duration isn't going to matter. I'd be
inclined to store the timestamp, it just seems more like the base datum.
regards, tom lane