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3 Posts
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3475
February 2nd, 2018 00:00
Why are there 3 clip IDs for the same clip?
I tried to add a document to an existing clip. Below are the details.
On adding the first document, the clip ID returned was :
059M50OMFHBGBeF0AF089HTK8S1G41C58BG4IA0H60KBCSOAH3STB
On adding the second document to the same clip, the ID returned was : CD4QCTM05DE7JeDSCEOUPSE1U7AG41C58C1Q340H60KBCSOAH3STB
On adding the third document to the same clip, the ID returned was : 6U24T9H8A43FOe7E4MVED1QIQ3EG41C58DBM490H60KBCSOAH3STB
On retrieval of documents, it was found that if we give the 1st clip ID, we were returned only the first document. If we gave the 2nd clip ID, we were returned the first and second document. So on, if we give the 3rd ID we were returned all the 3 documents.
It is understood that on adding new documents to an existing clip we would get a new Clip ID, but then how are we able to retrieve documents using the 1st and 2nd clip IDs. Shouldn't the old clip IDs become invalid?
So I want to know whether the 3 clip IDs correspond to 3 different C Clips or to 1 single clip. If they correspond to a single clip then why are we not able to get all the 3 documents from the 1st and 2nd clip id. Also is it possible to get the CDF of these clips for us to analyse.
mfh2
208 Posts
0
February 12th, 2018 06:00
Hello -
Centera C-Clip content is decomposed into CDFs (Clip Descriptor FIle metadata) and Blobs (binary attachments). Blobs can be shared across separate clips, which is what you are seeing in your test. ClipA only contains the pointer for BlobA. When you update ClipA to write ClipB (with pointers to both BlobA and BlobB) you now have 2 separate CDFs with 1 blob in common. If you want ClipA to "go away" when it gets updated you can call FPClip_Delete(ClipA); this is safe as Centera does reference counting and will not delete BlobA until all references have been deleted.
I suppose it's also worth mentioning that Centera is a 100% Fixed Content (i.e. WORM) platform. So you can't overwrite a committed clip or blob; when you 'update' you are always creating a new object with a new address and the previous version is still valid.
Hope this helps,
Mike Horgan
Maddy_234
2 Posts
0
February 14th, 2018 07:00
Hi,
Centera creates content address based on the content you upload. Every time you add/update a document, Centera will generate a new clip ID and older clip ID will not become inactive unless a 'delete' call is issued from Centera API.
For your last question, yes it is possible to get the CDF of all these clips, however, you need a root access for the same. Please reach out to DELL EMC support for any assistance around this. Hope this helps!
~Maddy
chiragdhawan
3 Posts
0
February 14th, 2018 20:00
But are all the 3 clip IDs for 3 different clips or do they correspond to 1 single clip?
chiragdhawan
3 Posts
0
February 14th, 2018 20:00
But are all the 3 clip IDs for 3 different clips or do they correspond to 1 single clip?
Maddy_234
2 Posts
0
February 15th, 2018 07:00
All the 3 clip IDs are different to each other since they correspond to different content (BLOB).