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From Mike Gallamore <mike.e.gallam...@googlemail.com>
Subject Re: writes to Cassandra failing occasionally
Date Thu, 08 Apr 2010 15:45:10 GMT
On 04/08/2010 04:53 AM, Philip Jackson wrote:
> At Wed, 07 Apr 2010 13:19:26 -0700,
> Mike Gallamore wrote:
>    
>> I have writes to cassandra that are failing, or at least a read shortly
>> after a write is still getting an old value. I realize Cassandra is
>> "eventually consistent" but this system is a single CPU single node with
>> consistency level set to 1, so this seems odd to me.
>>      
> I'm having this problem too (see my post the other day). I use N::C
> but generate timestamps in the same way as N::C::E, I've tested that
> each is smaller than the next so I'm wondering if I'm barking up the
> wrong tree.
>
> If you figure out what's going on please do post back here, I'll do
> the same.
>
> Cheers,
> Phil
>    
I modified N::C::E to output the timestamp each time the timestamp 
subroutine is called. I've confirmed that the timestamp is increasing 
(never getting two updates with the same timestamp) but I'm still 
loosing data.

This is painful because part of the data structure I'm working with is a 
revolving one week bucket of daily scores. When the system forgets that 
the day has changed it thinks it is still yesterday and "nukes" the data 
in that bucket (which it just set) thinking that it is week old data. 
The desired behavior of course is that it realize that it is a new day 
(this is stored in the data structure itself and isn't modifible as it 
depends on when the data was first created for a particular row which 
"bucket" the system will be working with any given day) and nuke the new 
day's old data before updating it with a new score.

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