Re: reindex/vacuum locking/performance?

On Sun, 2003-10-05 at 19:50, Neil Conway wrote:
> On Sun, 2003-10-05 at 19:43, Tom Lane wrote:
> > This would be relatively easy to fix as far as our own buffering is
> > concerned, but the thing that's needed to make it really useful is
> > to prevent caching of seqscan-read pages in the kernel disk buffers.

> For the non-portable way of doing this, are you referring to O_DIRECT?

I was hoping you'd reply to this, Tom -- you were referring to O_DIRECT,
right?

(If you were referring to O_DIRECT, I wanted to add that I wouldn't be
surprised if using O_DIRECT on many kernels reduces or eliminates any
readahead the OS will be doing on the sequential read, so the net result
may actually be a loss for a typical seqscan.)

-Neil