Re: [Tracker] Ontology change support upgrading nrl:maxCardinality 1 to multiple

[Philip Van Hoof <philip codeminded be>]

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Hi Everybody,

P.G.O. wont show it anymore, so here is my blog article describing the
feature a little bit:

http://pvanhoof.be/blog/index.php/2014/09/30/nrlmaxcardinality-one-to-many-ontology-changes
:-)

Good luck with the release that will contain the now supported
ontology change!

Kind regards,

Philip

On 24/09/2014 22:32, Philip Van Hoof wrote:
> Hi everyone,
>
> As many might have noticed in the changelog of 1.2.1 release we 
> decided to revert the nrl:maxCardinality change made on 08-28.
>
> That's because this ontology change force a reindex and removal of 
> your existing metadata. That's data loss for certain users, so not 
> acceptable for the majority of distributors distributing Tracker.
>
> A week or so ago I started with adding support for this kind of 
> ontology changes.
>
> Of course can't we ever in a reliable way support
> nrl:maxCardinality change from multiple to one: we'd lose type
> information if we'd only support it for CSV-like strings and for
> any other type we can't store the multiple old values in a single
> value solution. I don't aim to ever support this. I do aim to
> support the one to multiple use-case.
>
> People interested in this can go look here:
>
> https://git.gnome.org/browse/tracker/log/?h=maxcardinality-change-support
>
>  Right now it will change the ontology's introspection and it'll
> allow free passage of the change without aborts or critical
> warnings.
>
> What doesn't yet work is in the catacombes of cruelty, angst and 
> untold stories of brain torture, create_decomposed_metadata_tables,
> to detect that this particular change is taking place this time.
> And then do the rename of the table, create (without the columns of
> the old single value), ensure the multi-value table is already
> created and then finally copy the renamed table's single values to
> the multi-value table to end with dropping the renamed table.
>
> The code is there but it doesn't work.
>
> This I will probably debug until it works later this week. I
> silently hoping that somebody will beat me to it. I fear I will
> have to do this miserable create_decomposed_metadata_tables stuff
> one more time.
>
> Kind regards,
>
> Philip _______________________________________________ tracker-list
> mailing list tracker-list gnome org 
> https://mail.gnome.org/mailman/listinfo/tracker-list

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