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From Alejandro Perez <sp...@indextank.com>
Subject Re: Schemas diverging while dynamically creating CF.
Date Fri, 15 Apr 2011 21:13:22 GMT
Thanks for the quick response!. I will reconsider the schema.

However, the problem troubles me somehow. How are schema changes supposed to
be done? Should I serialize them, should I halt other cluster operations
while I do the schema change? Is this a known problem with cassandra?

The other question, and I think the more important one for me now: how do I
repair the cluster without loosing data once the schemas diverge? Right now
the only way I have is erase all data and have the cluster start empty.
Should this problem ever happen in production, it's important there's a way
to recover the data.

On Fri, Apr 15, 2011 at 1:57 PM, Dan Hendry <dan.hendry.junk@gmail.com>wrote:

> Uh... don’t create a column family per user. Column families are meant to
> be fairly static; conceptually equivalent to a table in a relational
> database. Why do you need (or even want) a CF per user? Reconsider your data
> model, a single column family with an inverted index for a ‘user’ column is
> probably more what you are looking for. Operationally, the fewer CFs the
> better.
>
>
>
> Dan
>
>
>
> *From:* Alejandro Perez [mailto:spike@indextank.com]
> *Sent:* April-15-11 16:39
> *To:* user@cassandra.apache.org
> *Cc:* Support
> *Subject:* Schemas diverging while dynamically creating CF.
>
>
>
> Hello,
>
>
>
> We're testing cassandra for integration with indextank. In this first try,
> we're creating one column family for each user. In practice, on the first
> run and for the first few documents (a few 100s), a new CF is created, and a
> document is immediately added to it. A few (up to 50) requests of this type
> are issued in parallel (for different column families).
>
>
>
> The end result, and quite repeatable, is having the cluster split with
> different schema versions, and they never agree.
>
>
>
> Any thoughts?
>
>
>
>
>
> Thanks,
>
>
>
> Spike.
>
>
> --
>
> Alejandro Perez
> IndexTank
>
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| subscribe
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>
>
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-- 
Alejandro Perez
IndexTank

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