[jbosscache-dev] migrating data stored in 1.x format to VAM format

[Manik Surtani]

On 4 Mar 2007, at 19:57, Galder Zamarreno wrote:

> I've got this working, including some basic unit tests and manual  
> examples to transform entired cache stores from 1.x data to 2.x.  
> These last manual examples include source code, 1.x cache stores  
> (file and jdbc derby db) and sample cache configurations.
>
> Apart from the MV issue referred earlier, I have realised that  
> TransformingJDBCCacheLoader will have to extend JDBCCacheLoaderOld  
> instead of JDBCCacheLoader.
>
> The reason is because when JDBCCacheLoader starts, if the root does  
> not exist, it'll create it, which in the  
> TransformingJDBCCacheLoader will mean creating it in 2.x format.
>
> This wouldn't be a problem if the root node didn't need querying  
> again, but if customers want to migrate their data, they will start  
> looping from the node (cache.getRoot()) and the first thing they'll  
> get its children. This results in trying to load the root node from  
> the cache store which breaks, as we're reading from db in 1.x format.
>
> Remember that the TransformingJDBCCacheLoader reads in 1.x format  
> and stores in 2.x format.
>
> This has a very easy resolution which is extending  
> JDBCCacheLoaderOld. After that, it works like a treat :).
>
> Manik, assuming you're happy with the original idea, would  
> extending JDBCCacheLoaderOld for this one off cache loader be ok  
> with you?

Yes, this makes sense, provided:

1)  These "utilities" are in a separate package and perhaps even a  
separate jar?  o.j.c.loader.migration.*?
2)  Even JDBCCacheLoaderOld (should be renamed to  
LegacyJDBCCacheLoader or something?  Mircea?) should be in this  
"migration" package.  I don't see anyone using it on an ongoing basis.

WDYT?

Cheers,
Manik