| From: | "Luke Lonergan" <llonergan(at)greenplum(dot)com> |
|---|---|
| To: | "Markus Schaber" <schabi(at)logix-tt(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Large tables (was: RAID 0 not as fast as |
| Date: | 2006-09-20 17:03:58 |
| Message-ID: | C136C28E.4E9%llonergan@greenplum.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
Markus,
On 9/20/06 1:09 AM, "Markus Schaber" <schabi(at)logix-tt(dot)com> wrote:
> Do you think that adding some posix_fadvise() calls to the backend to
> pre-fetch some blocks into the OS cache asynchroneously could improve
> that situation?
Nope - this requires true multi-threading of the I/O, there need to be
multiple seek operations running simultaneously. The current executor
blocks on each page request, waiting for the I/O to happen before requesting
the next page. The OS can't predict what random page is to be requested
next.
We can implement multiple scanners (already present in MPP), or we could
implement AIO and fire off a number of simultaneous I/O requests for
fulfillment.
- Luke
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Markus Schaber | 2006-09-20 18:02:06 | Re: Large tables (was: RAID 0 not as fast as |
| Previous Message | Chris Mair | 2006-09-20 15:47:41 | Re: running benchmark test on a 50GB database |