Very true, although "efficiency", in my mind, often covers at least both the
speed of computer operations and the speed of application development. {grin}
The experience I expressed has come out of curating a sphere of materials that
rarely change-- digitizations from archives. If I were using Fedora with a
fast-changing and complex resource graph, it might very well be worth the time
to actually compare the speed of updating various styles of persistence in my
actual setting. It's also worth pointing out that the default Low Level Store
and RI implementations are just as they are offered-- defaults. They can be
replaced with alternatives that take advantage of local strengths to achieve
better performance. For example, we redesigned our low-level stores for a large
repository to take advantage of certain local network-layer characteristics and
were very pleased with the results. I know that many Fedora institutions spend
time creating a RI implementation that is right for them.
---
A. Soroka
Online Library Environment
the University of Virginia Library
On Aug 31, 2011, at 3:46 PM, Greg Jansen wrote:
> One use case that applies in some areas, but not others, is the
> difficulty of reordering the contents. If you need to reorder or insert
> new children efficiently, then you'll probably want to keep that order
> in the parent. With all the indexing available in ri or elsewhere, one
> thought is to store things together that get changed in tandem.
>
> ___
> Gregory N. Jansen
> Developer - Carolina Digital Repository
> UNC Chapel Hill Libraries
>
>
> On 08/31/2011 03:35 PM, aj...@virginia.edu wrote:
>> Below is a section of RDF from a page-object. We keep this right in RELS-EXT
>> and let Fedora do the work of updating for us.
>>
>> ---
>> A. Soroka
>> Online Library Environment
>> the University of Virginia Library
>>
>> <rdf:RDF ... xmlns:uva="http://fedora.lib.virginia.edu/relationships#";>
>> <rdf:Description rdf:about="info:fedora/uva-lib:1038869">
>> ...
>> <uva:hasPreceedingPage
>> rdf:resource="info:fedora/uva-lib:1038868"/>
>> <uva:isFollowingPageOf
>> rdf:resource="info:fedora/uva-lib:1038868"/>
>> <uva:hasFollowingPage
>> rdf:resource="info:fedora/uva-lib:1038870"/>
>> <uva:isPreceedingPageOf
>> rdf:resource="info:fedora/uva-lib:1038870"/>
>> ...
>> </rdf:Description>
>> </rdf:RDF>
>>
>> On Aug 31, 2011, at 3:25 PM, Scott Prater wrote:
>>
>>> Hi, Adam --
>>>
>>> Can you give us a sample of the double linked-list triples? I'd like to
>>> see how you express that in RDF.
>>>
>>> Is this something you express in the RELS-EXT, or triples you add to the RI
>>> outside Fedora?
>>>
>>> thanks,
>>>
>>> -- Scott
>>>
>>> On 08/31/2011 02:18 PM, aj...@virginia.edu wrote:
>>>> I agree with Scott's point that "page sequences can be considered a
>>>> property of containers ... rather than a property inherent in the page
>>>> object itself", and because of a well-known updating difficulty in the RI,
>>>> it is not possible to use RDF containers in RELS-*. See:
>>>>
>>>> https://jira.duraspace.org/browse/FCREPO-656
>>>>
>>>> There is, however, a fair way to use the RI to this end-- you can
>>>> construct a linked list, or a doubly-linked list amongst the pages. That's
>>>> what we do (a doubly-linked list). We're therefore relying on the RI to be
>>>> fast, which it is (it is, after all, an _index_-- the repository is the
>>>> data store). Updating is fairly easy (create object with two
>>>> relationships, then alter four relationships of the preceding and
>>>> following pages). We have no trouble querying into the RI for results fast
>>>> enough for a page-turner presentation.
>>>>
>>>> But then, we are strongly committed to RDF for as much structural metadata
>>>> as we can cram into it. {grin}
>>>>
>>>> ---
>>>> A. Soroka
>>>> Online Library Environment
>>>> the University of Virginia Library
>>>>
>>>>
>>>>
>>>>
>>>> On Aug 31, 2011, at 2:11 PM, Scott Prater wrote:
>>>>
>>>>> Hello, Joszef --
>>>>>
>>>>> I'll send you a couple of sample objects in a separate email.
>>>>>
>>>>>> Not to mention, that I don't really have a clear vision, how to store
>>>>>> page orders in RELS... :)
>>>>> Nor do we. You could store the sequence triple in the object itself,
>>>>> something along the lines of<myobject> <hasPageSequence> "1", but then
>>>>> you'd have to query every single object to build a list of pages (not a
>>>>> real big deal in the resource index, but still, a little clunky). And
>>>>> what if you forget to scan a page, and your numbering gets all whacked,
>>>>> and you have to go back and add a page later (something that occurs more
>>>>> often than we would like to admit)? You'll need to update the page
>>>>> sequence triple in every following page object.
>>>>>
>>>>> An even more subtle problem crops up if your object has one page number
>>>>> in one context (say, a plate in a book) and another page number in
>>>>> another context (say, the same plate in an art exhibit catalogue): if
>>>>> you were to create these two relations in the page object, how would you
>>>>> express in a triple that I'm page 1 of book A, and page 3 of book B?
>>>>> This is a use case which demonstrates that page sequences can be
>>>>> considered a property of containers ("I'm a book, and I have this
>>>>> content at position X"), rather than a property inherent in the page
>>>>> object itself.
>>>>>
>>>>> That would be okay, except that there's no way to express in a book
>>>>> object's RELS-EXT triple that book object A contains page object A1 with
>>>>> the attribute page sequence "1". You can do that in METS, though.
>>>>>
>>>>> -- Scott
>>>>>
>>>>>
>>>>> --
>>>>> Scott Prater
>>>>> Library, Instructional, and Research Applications (LIRA)
>>>>> Division of Information Technology (DoIT)
>>>>> University of Wisconsin - Madison
>>>>> pra...@wisc.edu
>>>>>
>>>>> ------------------------------------------------------------------------------
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>>>>> Finally, a world-class log management solution at an even better
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>>>>
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>>>
>>> --
>>> Scott Prater
>>> Library, Instructional, and Research Applications (LIRA)
>>> Division of Information Technology (DoIT)
>>> University of Wisconsin - Madison
>>> pra...@wisc.edu
>>
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