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

[John Bestevaar <Josephus people net au>]

Hi Philip
I do hope i am not out of order here as i am not a code person.
My sympathies with your present situation and the misery of it.
If you will indulge me in stating the bleeding obvious: Solving this 
kind of dilemma is what people do but code cannot do by itself. So for 
me the marvels of the internet age are the people and not the fancy 
though most useful programs and applications.

Kind Regards John Bestevaar

On 25/09/14 06:32, Philip Van Hoof wrote:
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> 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
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