Ron Mayer wrote: > Martijn van Oosterhout wrote: > > > > Well, you get another issue, alignment. If you squeeze your string > > down, the next field, if it is an int or string, will get padded to a > > multiple of 4 negating most of the gains. Like in C structures, there > > is padding to optimise access. > > Anecdotally I hear at least as many people say that their database > is more I/O bound than CPU bound; and it seems that adding bytes > for alignment is a way of reducing CPU for more disk I/O. > > I guess unaligned access so expensive that it makes up for the extra i/o?
This is a good point. We have always stored data on disk that exactly matches its layout in memory. We could change that, but no one has shown it would be a win. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
