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From Yang <teddyyyy...@gmail.com>
Subject Re: custom reconciling columns?
Date Tue, 28 Jun 2011 22:37:09 GMT
I can see that as my user history grows, the reads time proportionally ( or
faster than linear) grows.
if my business requirements ask me to keep a month's history for each user,
it could become too slow.----- I was suspecting that it's actually the
serializing and deserializing that's taking time (I can definitely it's cpu
bound)



On Tue, Jun 28, 2011 at 3:04 PM, aaron morton <aaron@thelastpickle.com>wrote:

> 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 ?
>
> Cheers
>
>
> -----------------
> Aaron Morton
> Freelance Cassandra Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> 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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