| From: | Mark Kirkwood <markir(at)paradise(dot)net(dot)nz> |
|---|---|
| To: | Luke Lonergan <llonergan(at)greenplum(dot)com> |
| Cc: | stange(at)rentec(dot)com, Greg Stark <gsstark(at)mit(dot)edu>, Dave Cramer <pg(at)fastcrypt(dot)com>, Joshua Marsh <icub3d(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Hardware/OS recommendations for large databases ( |
| Date: | 2005-11-22 05:10:24 |
| Message-ID: | 4382A840.3030401@paradise.net.nz |
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| Lists: | pgsql-performance |
Luke Lonergan wrote:
> So that leaves the question - why not more than 64% of the I/O scan rate?
> And why is it a flat 64% as the I/O subsystem increases in speed from
> 333-400MB/s?
>
It might be interesting to see what effect reducing the cpu consumption
entailed by the count aggregation has - by (say) writing a little bit
of code to heap scan the desired relation (sample attached).
Cheers
Mark
| Attachment | Content-Type | Size |
|---|---|---|
| fastcount.c | text/plain | 978 bytes |
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