On Tue, Aug 25, 2015 at 10:16:37AM PDT, Andomar wrote: > >However, I know from experience that's not entirely true, (although it's not always easy to measure all aspects of your I/O bandwith). > > > >Am I missing something? > > > Two things I can think of: > > Transaction writes are entirely sequential. If you have disks > assigned for just this purpose, then the heads will always be in the > right spot, and the writes go through more quickly. > > A database server process waits until the transaction logs are > written and then returns control to the client. The data writes can > be done in the background while the client goes on to do other > things. Splitting up data and logs mean that there is less chance > the disk controller will cause data writes to interfere with log > files. > > Kind regards, > Andomar > hmm, yeah those are both what I'd lump into "I/O bandwith". If your disk subsystem is fast enough, or you're on a RAIDd SAN or EBS you'd either overcome that, or not neccssarily be able to. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
