[GSoC] migration

[Umesh Singla]

Hi Josh,

        And then again, I am sensing a confusion with the idea of
>>         snapshot with Josh, like when he says "remove ports when they
>>         are no longer referenced by any snapshot".
>>
>>
>>     What confusion exactly? A snapshot is simply a set of ports (by
>>     which I mean rows in the 'ports' table, with a unique combination of
>>     name,version,revision,variants). When nothing references a row any
>>     more, it needs to be deleted.
>>
>>
>> By 'ports', do you mean 'registry.ports' table? If yes, then I disagree.
>> It's actually 'registry.snapshot_ports' table. A snapshot has nothing to do
>> with the original registry "tables".
>>
>
> That was a suggested design; if you're already doing it differently then I
> guess you don't need a design. I disagree with the last sentence though, a
> snapshot can be viewed as precisely the state of the original tables at a
> previous time.


This is on the lines what I had in mind regarding a snapshot.

Also, we are not using version and revision. Even going by the literal
>> meaning of a snapshot, it should not have a key or id linked to something
>> that can change over time. It's simply the present state.
>>
>
> The row in the ports table would not change over time, it would simply
> persist until no longer needed. If we ever get the ability to install old
> versions then that information would come in handy.


I meant when the port gets updates, the row in the 'ports' table will
change but not in 'snapshot_ports' table because for a particular snapshot,
the state has changed. But I think it's clear now.

And yes, version and revision can help in restoring older versions of ports
present in older snapshots.


> Later, I am planning to keep information on the manual portgroups in the
>> snapshot, if there are any.
>>
>
> What would this information be used for?
>

I am under the impression that a user can categorize and classify the ports
into portgroups, so it should be better if we migrate them too. Though, it
seems highly unlikely now that I write and quite possible I need to learn
about them more.

Regards,
Umesh Singla
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