Re: Data Buffer Cache

Mon, 16 Sep 2002 18:42:38 +1000, Howard J. Rogers said (and I quote):

> Quite so, and my standard advice is precisely this... but that's because the
> I/O associated with any checkpoint (ie, log switch) is obviously an overhead
> that must be paid for in performance, not because the database actually
> grinds to a halt waiting for a checkpoint to finish.

Hmmm, it's the best impersonation of grinding to a halt I've ever seen... ;)

>
> This would seem to be a common misapprehension amongst newbies: "database
> processing actually stops at a checkpoint, and then resumes when it's
> finished, doesn't it?". Nope, but it's agreed that making the database do
> any 'housekeeping' work means there's less grunt for processing your data.

That is in fact correct. I'm just being a little cynical. After all, I'm in Oz-land, no? <G>
But the drop in performance at least in all versions up to 8iR3 when a checkpoint or log switch happens is totally out of context with a wait for a few I/Os. There is a LOT more going on there...

-- 
Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam