urn:urn|uuid versus regular(?) uuid

At_Libitum · 10-16-2013, 09:25 AM

I have a question.

I previously assumed that the uuid I see in the identifiers field (urn:urn|uuid) was the same as the uuid value shown in the book details panel. In fact I never bothered to check if they were one and the same but because it shows the same format I never payed much attention to it since it is to me meaningless data.

However, in trying to synchronize the various libraries I have with regards to custom columns, I created a view which shows every field in library view and now that I have these fields side by side I suddenly notice they have each a completely different value?

What is the idea behind these fields and why do they differ for the same book?

kovidgoyal · 10-16-2013, 11:00 AM

There's no connection. One is a calibre internal indetifier and the other comes from the the opf inside the epub.

At_Libitum · 10-16-2013, 11:13 AM

thank you for the explanation.

This raises the next question, although I think I'll know the answer already.

When copying from one library to another, is either of them used to determine if that book already exists? or is this based on just Author/Title/Format?

kovidgoyal · 10-16-2013, 11:16 AM

Author/title, there's not much point searching on uuid, it is just a randomnly generated number. It will not be the same for two copies of the same book in different libraries.

At_Libitum · 10-16-2013, 07:47 PM

thanks for confirming.

10-16-2013, 09:25 AM	#1
At_Libitum Addict Posts: 265 Karma: 724240 Join Date: Aug 2013 Device: KyBook	urn:urn\|uuid versus regular(?) uuid I have a question. I previously assumed that the uuid I see in the identifiers field (urn:urn\|uuid) was the same as the uuid value shown in the book details panel. In fact I never bothered to check if they were one and the same but because it shows the same format I never payed much attention to it since it is to me meaningless data. However, in trying to synchronize the various libraries I have with regards to custom columns, I created a view which shows every field in library view and now that I have these fields side by side I suddenly notice they have each a completely different value? What is the idea behind these fields and why do they differ for the same book?

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10-16-2013, 11:00 AM	#2
kovidgoyal creator of calibre Posts: 45,300 Karma: 27111240 Join Date: Oct 2006 Location: Mumbai, India Device: Various	There's no connection. One is a calibre internal indetifier and the other comes from the the opf inside the epub.

10-16-2013, 11:13 AM	#3
At_Libitum Addict Posts: 265 Karma: 724240 Join Date: Aug 2013 Device: KyBook	thank you for the explanation. This raises the next question, although I think I'll know the answer already. When copying from one library to another, is either of them used to determine if that book already exists? or is this based on just Author/Title/Format?

10-16-2013, 11:16 AM	#4
kovidgoyal creator of calibre Posts: 45,300 Karma: 27111240 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Author/title, there's not much point searching on uuid, it is just a randomnly generated number. It will not be the same for two copies of the same book in different libraries.

10-16-2013, 07:47 PM	#5
At_Libitum Addict Posts: 265 Karma: 724240 Join Date: Aug 2013 Device: KyBook	thanks for confirming.

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