Rethinking relationsips in XMP-ics data?

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Mke
Posts: 470
Joined: 15 Jun 14 15:39

Rethinking relationsips in XMP-ics data?

Post by Mke » 30 Jan 20 18:25

PSU has the very useful ability to add relationships between labels. However, as the number of relationships grow, I'm wondering if the way that these are currently written to XMP-ics could be changed to avoid excessive data redundancy.

To outline the issue:

Take a child label which is 'related to' a parent label, and apply them both to an image. This results in every child of the parent being recorded in the XMP-ics data for that image.

For example, in my catalogue the label Queen Victoria public house is 'related to' the generic label pub. If I apply both labels to an image then the XMP-ics data for that image includes details of every specific pub 'related to' pub in my catalogue.

At the moment pub is only in 20 relationships in my catalog, but in time it's likely to reach hundreds - all of them cross-referencing each other in the XMP-ics data. And the same for each other set of relationships. That's going to grow into a very large amount of redundant data (in the technical sense of data redundancy).

Should consideration be given to (optionally?) handling this in a different way? Perhaps:
  • Only recording the single relationship from 'child' to 'parent' in the XMP-ics data (my favorite provided the 'direction' of the relationship can be determined)?
  • Optionally excluding relationships from XMP-ics?
  • Enabling relationship data to be separately exported, in a similar way to the way that the catalog label hierarchy can be exported to a file?

Hert
Posts: 5987
Joined: 13 Sep 03 7:24

Re: Rethinking relationsips in XMP-ics data?

Post by Hert » 31 Jan 20 12:08

The only goal for writing ICS is so that PSU can recover catalog information from that section in case of *absolute* emergency.
The ICS in every file should be considered as its own "mini" catalog. The world for ICS doesn't go broader than what is in the file. Relationships are part of the catalog and so are also written to ICS.

The choice you have is "do I want this extra safety backup of my catalog in the files or not?". Or in other words: do I want ICS or not. If you have good backup strategies and are confident that you can always recover without ICS, then there's absolutely no need to write ICS.
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Mke
Posts: 470
Joined: 15 Jun 14 15:39

Re: Rethinking relationsips in XMP-ics data?

Post by Mke » 31 Jan 20 15:19

I agree with you Hert.

And as XMP-ics is for emergency use only, it only needs to contain the data strictly necessary to reinstate that single image in a new catalogue.

At the moment, for relationships, it goes way beyond that. One image contains the data required to rebuild the entire related family, be that a family of 2 or of 2,000.

In human terms, to rebuild a family, all a child needs to know is that "my parent is P". By collating everyone with parent P, the family can be recreated.

It's not necessary for every child to have a list saying "my parent is P and my siblings are A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z, AA, AB, AC, AD, AE, AF, AG, AH, AI, AJ, AK, AL, AM, AN, AO, AP, AQ, AR, AS, AT, AU, AV, AW, AX, AY, AZ, AAA, AAB, AAC, AAD, AAE, AAF, AAG, AAH, AAI, AAJ, AAK, AAL, AAM, AAN, AAO......"

Of course it works perfectly well, it's just a bit paranoid :)

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