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From aaron morton <>
Subject Re: custom reconciling columns?
Date Tue, 28 Jun 2011 22:04:03 GMT
There is no facility to do custom reconciliation for a column. An append style operation would
run into many of the same problems as the Counter type, e.g. not every node may get an append
and there is a chance for lost appends unless you go to all the trouble Counter's do. 

I would go with using a row for the user and columns for each item. Then you can have fast
no look writes. 

What problems are you seeing with the reads ?


Aaron Morton
Freelance Cassandra Developer

On 29 Jun 2011, at 04:20, Yang wrote:

> for example, if I have an application that needs to read off a user browsing history,
and I model the user ID as the key,
> and the history data within the row. with current approach, I could model each visit
as  a column, 
> the possible issue is that *possibly* (I'm still doing a lot of profiling on this to
verify) that a lot of time is spent on serialization into the message and out of the
> message, plus I do not need the full features provided by the column : for example I
do not need a timestamp on each visit, etc,
> so it might be faster to put the entire history in a blob, and each visit only takes
up a few bytes in the blob, and 
> my code manipulates the blob.
> problem is, I still need to avoid the read-before-write, so I send only the latest visit,
and let cassandra do the reconcile, which appends the
> visit to the blob, so this needs custom reconcile behavior.  
> is there a way to incorporate such custom reconcile under current code framework? (I
see custom sorting, but no custom reconcile)
> thanks
> yang

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