Alessio Bragadini wrote: > On Sat, 2002-10-12 at 11:37, Gavin Sherry wrote: > > > I cannot think of any reason why changing column order should be > > implemented in Postgres. Seems like a waste of time/more code bloat for > > something which is strictly asthetic. > > > > Regardless, I do have collegues/clients who ask when such a feature will > > be implemented. Why is this useful? > > Has column ordering any effect on the physical tuple disposition? I've > heard discussions about keeping fixed-size fields at the beginning of > the tuple and similar. > > Sorry for the lame question. :-)
Yes, column ordering matches physical column ordering in the file, and yes, there is a small penalty for accessing any columns after the first variable-length column (pg_type.typlen < 0). CHAR() used to be a fixed length column, but with TOAST (large offline storage) it became variable length too. I don't think there is much of a performance hit, though. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (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 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
