Alvaro Herrera wrote: > On Wed, Mar 23, 2005 at 10:42:01AM +0800, Christopher Kings-Lynne wrote: > > >>If you want to be my friend forever, then fix CLUSTER so that it uses > > >>sharerowexclusive as well :D > > > > > >I don't think it's as easy as that, because you have to move tuples > > >around in the cluster operation. Same sort of issue as vacuum full I > > >would suggest. > > > > Cluster doesn't move rows... > > > > I didn't say it was easy. It would involve changing how cluster works. > > It would keep the old table around while building the new, then grab > > an exclusive lock to swap the two. > > Huh, cluster already does that. > > I don't remember what the rationale was for locking the table, leaving > even simple SELECTs out. (In fact, IIRC the decision wasn't made by me, > and it wasn't discussed at all.) >
The issue is that we would have to escalate the shared lock to exclusive to swap out the files, and lock escallation could lead to deadlock/starvation. -- 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 8: explain analyze is your friend
