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From Antony Blakey <antony.bla...@gmail.com>
Subject Re: couchdb transactions changes
Date Tue, 10 Feb 2009 00:23:26 GMT

On 10/02/2009, at 10:30 AM, Paul Davis wrote:

> Alas it is true, if you have a system that has operating
> characteristics that involved a write load that far outweighs the read
> load

I don't think it has to far outweigh it, just exceed it. And in any  
case, that's assuming that there's a single reader. With replication  
you might have many readers doing duplicate reads, which means that  
the effective read rate w.r.t the write rate is divided by the number  
readers.

For example consider that you have 100 replication readers. Each  
reader will advance at 1/100'th the rate of a single reader. So the  
write rate only has to be > 1% of the theoretical read rate to exceed  
the effective read rate/progress of the individual replicators.

And that's ignoring the fact that the effective read rate for  
replication is dependent on bandwidth and connectivity e.g throughput  
is not the same as raw read rate in any case.

Antony Blakey
-------------
CTO, Linkuistics Pty Ltd
Ph: 0438 840 787

All that is required for evil to triumph is that good men do nothing.



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