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From Giancarlo Frison <gfri...@chelab.com>
Subject Re: compatibility with evolved schemas
Date Thu, 28 Jul 2011 08:42:04 GMT
Thank you very much Dough and Scott,

On Wed, Jul 27, 2011 at 11:16 PM, Scott Carey <scottcarey@apache.org> wrote:

> The code needs both schemas, and then it can resolve the difference between
> the schemas and read the old data using the new schema.
>
> In the Java API this usually means passing the old 'writer' schema as well
> as the new 'reader' schema to the object responsible for reading the data.
>
> As Doug described, the 'writer' schema must be available somehow, either by
> storing it with the data or from a reference.  For example, the Avro Data
> File format stores the schema that all records in the file conform to in the
> file header.  Then any reader can discover the written schema when opening
> the file.
>
> -Scott
>
> On 7/27/11 3:24 AM, "Giancarlo Frison" <gfrison@chelab.com> wrote:
>
> Hi all,
>
> I'm wondering if it's possible to load stored records with extends schemas.
> If I store a record with 3 fields, is it possible by any chance to load it
> by an extended schema definition (for instance with one field more)?
> I tried it but the serialized record is unreadable by the newest schema.
> What I can do to accomplish this purpose?
>
> thanks,
>
> --
>
> Giancarlo Frison
>
> http://gfrison.com
>
>


-- 

Giancarlo Frison

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