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From Damien Katz <>
Subject Re: document insert rate
Date Sun, 04 Jan 2009 22:38:31 GMT

On Jan 4, 2009, at 4:11 PM, Geir Magnusson Jr. wrote:

> On Jan 4, 2009, at 2:59 PM, Damien Katz wrote:
>> What you say is possible, but doesn't seem too likely as I don't  
>> ever recall any report of a corrupt db on Linux, but before the  
>> F_FILESYNC change in Erlang we would see reports of corruptions on  
>> OS X due to power loss. Since the change, we've had no reports of  
>> corrupt databases on OS X or Linux.
> Have you seen the correlation between the # of pirates and global  
> warming? :)
> There may be correlation here between the Erlang update and  
> corruption, but I don't see the causality -  fsync() on linux should  
> only get as far as the on-device buffering if it does write  
> buffering, whereas if the OS X docs are truthful, the F_FILESYNC  
> fcntl() pushs the bits to the rust on the platter.  Maybe they fixed  
> something else in that erlang update, or maybe the universe is  
> smiling upon CouchDB users or ....
>> I don't think anyone else sees update performance that slow (I'm  
>> assuming these are fairly small documents?), I'd guess there is  
>> something particular about your setups. Since it involves update  
>> speed it wouldn't be the javascript engine. It's possible it's the  
>> openssl interface, I've seen instances of wacked openssl installs  
>> that slowed down Erlang but didn't crash it.
> I have an idea.... try it. I bet you can't get better than that  
> (6-8  inserts per second) on Mac OS X unless you have stupid-fast  
> disks (like maybe an SSD).
> Even get a "back of the envelope" approx using time and curl - that  
> came in at the same rate as Ruby, JS and Java test programs.
> Everyone who has tried my experiment on IRC has reported the same  
> numbers.  I can get 6/sec on a laptop (2.5GHz core2 dual core MBP w/  
> 4GB ram and a 7200rpm disk), and 8/sec on my desktop (a quad-core, 8  
> GB w/ raided 7200rpm disks, IIRC)
> geir

Okay, very well. If you find evidence this is broken on Linux systems,  
please file a bug.


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