No, but disks are about 120 MB/s speed, peak writes during CHECKPOINT are only 20-30 MB/s, and there is no disk read activity at all, so - no matter where the xlog resides.
But now seems bgwriter tuning gets some effect, CHECKPOINT is running faster (about 2-3 seconds instead of 10-15). It is still beats the performance, but less.
On 3/29/07, CAJ CAJ <pguser@gmail.com> wrote:
On 3/28/07, Joseph S <jks@selectacast.net> wrote: Dmitry Koterov wrote:
> And the general question - why SELECT queries slowdown during the
> CHECKPOINT? I thought that Postgres is a version-based database and read
> queries are never blocked...
Because the disk is busy.
Is your pg_xlog on a separate disk?