I don't have any numbers; and it may be an misconception as you pointed out that's out there among Oracle DBAs that need to be re-visited again. Tom, could you also explain what you meant in a previous post I found during my research on this issue, which I may have misunderstood it: "I actually wish that Postgres would preallocate a lot of blocks in advance (ie. 100 x 8KB). That would probably improve performance, as it would not have to keep re-extending the file." http://archives.postgresql.org/pgsql-interfaces/2001-01/msg00153.php Thanks, -- Husam -----Original Message----- From: Tom Lane [mailto:tgl@xxxxxxxxxxxxx] Sent: Monday, October 31, 2005 7:59 PM To: Scott Marlowe Cc: Tomeh, Husam; pgsql-admin@xxxxxxxxxxxxxx Subject: Re: Vacuum Verbose output Scott Marlowe <smarlowe@xxxxxxxxxxxxxxxxx> writes: > On Mon, 2005-10-31 at 16:34, Tomeh, Husam wrote: >> Pre-allocating space will prevent extending the datafile during >> loading massive data (batch processing) and would improve the overall >> batch write performance. > Have you got any file system benchmarks that back up this assertion? I > would love to see something that shows one way or the other if that > really makes any difference. Barring some pretty solid evidence, you're unlikely to attract any enthusiasm among pghackers for this sort of thing. We are generally disinclined to reinvent functionality that properly belongs to the kernel or filesystem layer. "Oracle does it" cuts no ice in this connection, because Oracle is designed around a twenty-year-old assumption that the database is smarter than the kernel, and the world has changed a lot since then. In short: show us some numbers that prove this is worth our attention. regards, tom lane ********************************************************************** This message contains confidential information intended only for the use of the addressee(s) named above and may contain information that is legally privileged. If you are not the addressee, or the person responsible for delivering it to the addressee, you are hereby notified that reading, disseminating, distributing or copying this message is strictly prohibited. If you have received this message by mistake, please immediately notify us by replying to the message and delete the original message immediately thereafter. Thank you. FADLD Tag ********************************************************************** ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
