On 12 Feb 2009, at 15:50, Wout Mertens wrote:
On Feb 12, 2009, at 3:13 PM, Kenneth Kalmer wrote:
Normal filesystem-based storage of mail has other issues:
* Messages often smaller than ethernet jumbo frames, so limited
throughput
(couch can overcome this by bundling messages in a single response)
wow that's really specialized. Is that really an issue?
* Mostly limited by disk IO and clever tricks around solid state
drive usage
or stripping excessively fast disks
Hmmm makes me wonder - CouchDB doesn't change the position of
received documents on disk, so retrieving a view could mean many
disk accesses.
Is that correct? Is that something all databases suffer from? I
suppose the only answer for that is caching?
The file and b-tree structure is actually made to require a minimal
number of disk head seeks (which is what makes disks slow) and
in a typical usage scenario, upper nodes of the btree are cached
in the filesystem buffer cache too, so there's another speedup.
Cheers
Jan
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