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From Boris Yen <yulin...@gmail.com>
Subject Re: DyanmicCompositeType bug?
Date Mon, 05 Dec 2011 09:47:34 GMT
It looks like using the dynamicComposite is a dangerous action. However,
one mistaken insertion causes the database to corrupt seems a little bit
too much. Is there anyway to just skip the wrong column.

On Mon, Dec 5, 2011 at 5:31 PM, Sylvain Lebresne <sylvain@datastax.com>wrote:

> On Mon, Dec 5, 2011 at 8:19 AM, Boris Yen <yulinyen@gmail.com> wrote:
> > Hi,
> >
> > I am using 0.8.7.
> >
> > I was trying to use DynamicComposite column. After I intentional added a
> > column (string:string:uuid) into a record which has previous columns
> > inserted with comparator (string:uuid:uuid). I got an exception on the
> > cassandra side and an timeout exception on the client (I was actually
> > expecting an validation exception on the client).
>
> By design, the DynamicComposite comparator cannot return a validation
> exception in that case. Or rather, since there is nothing specifying how
> a column should look like, the only way we could ever hope to return a
> validation exception would be to scan the entire row on insertion (which
> is out of question).
>
> > After that when I re-started cassandra, cassandra kept saying that
> > "comparator mismatch while comparing two dynamicCompositeType column..."
> and
> > cassandra never really got started.
> >
> > Is this a bug?
>
> No. As said above, this is something we cannot do anything about.
> The DynamicCompositeType comparator is by nature a very dangerous
> one. One column inserted in the wrong row can corrupt that row (with
> recovery involving losing data).
> In other words, don't use DynamicCompositeType. Don't use it unless
> you are absolutely sure you won't ever insert the wrong column in the
> wrong row *and* you absolutely need the DynamicCompositeType (by
> opposition to the faster, cheaper and safe CompositeType). And if you
> do, you have to assume the consequence if you do mess up.
>
> --
> Sylvain
>
> --
> Sylvain
>

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