El lunes, 29 de agosto de 2016, Tim Robertson trobertson@gbif.org escribió:
(...) I’m afraid it is a little messy, but I will try and explain.
The original thinking by the DwC authors was that *dwc:occurrenceID* would be used to identify an occurrence in nature, while *dc:identifier* would be a digital record identifier. (...) If a provider adds occurrenceID and leaves those 3 fields the same, we will recognise this and update the records. If they were to remove one of those triplets, we would insert new records and the old ones would be deleted at some point. It is a manual process to allow us to engage with publishers before running deletions.
Thanks Tim. I understood your explanation about occurrenceID / identifier differences.
Can you elaborate a bit more on what happens if a provider using triplets decides to add occurrenceID? You said GBIF reindex (1st reindex) will recognize them and update the records. What if LATER ON (after 1st reindex) a record is changed so occurrenceID KEEPS STABLE but the triplet value is deleted or modified? Shouldn't next GBIF reindex (2nd and later) keep using the already extant occurrenceID? So, the record should be updated, not inserted.
From your comment I understood it would be inserted but I guess you meant
that happens if both changes (occurrenceID added + triplet changed) are done at the same time (same GBIF reindex). Would this two steps strategy make a difference to avoid us asking you to delete records?
And yes, I think it makes sense to use some kind of UUIDs for occurrenceID values. I understand these only need to be unique only in the dataset context, but its better to make them globally unique for linking purposes, right?
Thanks for your help, and indeed for the new incoming GBIF filtering options
David
I notice that the dataset you linked to was published in 2007, before dwc:occurrenceID existed. It is therefore using the *dwc:insitutuionCode* , *dwc:collectionCode* and *dwc:catalogNumber *identifier strategy.
Please note, that Darwin Core recommends concatenating the 3 fields to create a *dwc:occurrenceID*. Please be aware that this approach means that should someone chose to e.g. change the collection code, the occurrence record ID will also change thus removing all linkability. If this is expected, then forging unique ids for records using e.g. UUIDs or similar would be a more robust longer term solution and in general we recommend targeting this.
We do recommend people strive to provide occurrenceID, even on older data. This simplifies things going forward.
I hope this helps, but please feel free to ask me any questions around this.
This is off topic, but while you are reading please know that we expect stateOrProvince to be a filter on GBIF next week along with locality, protocol, license, organismID, publishingOrgKey (API only), crawlID (API only). I know you have interest in this functionality.
Best wishes, Tim
From: API-users <api-users-bounces@lists.gbif.org javascript:_e(%7B%7D,'cvml','api-users-bounces@lists.gbif.org');> on behalf of Herbario SANT <sant.herbarium@gmail.com javascript:_e(%7B%7D,'cvml','sant.herbarium@gmail.com');> Date: Sunday 28 August 2016 at 16:00 To: "api-users@lists.gbif.org javascript:_e(%7B%7D,'cvml','api-users@lists.gbif.org');" < api-users@lists.gbif.org javascript:_e(%7B%7D,'cvml','api-users@lists.gbif.org');> Subject: Re: [API-users] What happens to previous data after dataset/crawl?
Hi
I take the opportunity to ask about the difference between two GBIF terms:
What is the difference of "occurrenceID" compared to "identifier"? Both have the same value in this dataset: http://www.gbif.org/occurrence/1291766512/verbatim http://api.gbif.org/v1/occurrence/1291766512
I see "occurrenceID" well explained here: http://gbif.blogspot.com.es/2014/04/ipt-v21.html http://rs.tdwg.org/dwc/terms/#occurrenceID
But I can't find the explanation for "identifier", which I think some institutions have been incorrectly understanding as "occurrenceID". For example: http://www.gbif.org/occurrence/142907792/verbatim http://api.gbif.org/v1/occurrence/142907792
There is an "identifier" in that occurrence, but no "occurrenceID".
- What is exactly the meaning of that "identifier"? Why is it not
explained in dwc terms page? 2) What happens if the data provider keeps all data UNCHANGED, but adds the "occurrenceID" which was missing? Would next GBIF reindex keep the same number of records and add their occurrenceIDs? (perhaps looking at the triplet in that "identifier"?) Would later on be safe to change any fields in the dataset (even "identifier", "catalognumber", ...) if that data provider keeps those occurrenceIDs stable?
Thanks
On 27 August 2016 at 08:01, Roderic Page <Roderic.Page@glasgow.ac.uk javascript:_e(%7B%7D,'cvml','Roderic.Page@glasgow.ac.uk');> wrote:
Just wanted to check the consequences of the following dataset operation.
Say I have a dataset with 10 occurrences with occurrence ids 1-10. In my local database I now assign those 10 occurrences new identifiers a-j. If I create a new DwCA file for my data and crawl the new archive, my expectation is:
- Old data with ids 1-10 is deleted from GBIF index
- New data with ids a-j is indexed
So, end result is dataset has 10 occurrences. I'm asking because I know in the past the some datasets have changed identifiers and this has resulted in records with old and new identifiers coexisting in GBIF index, resulting in duplicated data.
Obviously it would be nice to have stable, unchanging identifiers for occurrences, but the for data set I'm working with the creators have changed their minds between versions of the data :(
Regards,
Rod
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