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Globbing, sorting and paging #956
Description
Would it be possible to add query parameters for sorting and paging when requesting a "globbing" resource?
When presenting a list of items (blog comments, chat entries, pets, whatever), it is very common to let the server do paging and sorting to improve efficiency for browsing through large amounts of data (as compared to loading all N-thousand Turtle statements and throw away 99% of them in order to show the top 1%).
It could work as follows:
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A globbing request like "/items/*" normally returns the Turtle content of all resources stored under "/items". Each of theses resources contains a set of Turtle statements.
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One URL parameter, like for instance "orderBy", could define a predicate identifier (or multiple) to order the resources by.
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Other URL parameters, like for instance "count" and "offset" could define which "slice" of the sorted resources to return.
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As a result, only the content of the first "count" resources, from index "offset", when ordering the resources by the value of the predicates in the resources by "orderBy", would be returned.
Example, get the first 10 items ordered by the value of http://schema.org/name: /items/*?orderBy=https%3A%2F%2Fschema.org%2Fname&offset=0&count=10
The "orderBy" predicate is only evaluated for statements where the subject is identical to the resource URL.
I kind of assume this suggestion is covered in existing work on linked data.
Activity
JornWildt commentedon Nov 20, 2018
I believe it is different from SPARQL in that it relates to whole resources instead of single statements - a granularity which is quite different from a giant un-organized set of statements for which SPARQL normally is used (AFAIK).
RubenVerborgh commentedon Nov 20, 2018
Unless you consider a document a graph and do a
CONSTRUCTover the graphs you want 🙂JornWildt commentedon Nov 20, 2018
Does that mean it (paging and sorting) is doable with the Solid server as it is today? It would be great to know how.
RubenVerborgh commentedon Nov 20, 2018
No not yet; Solid servers do not support SPARQL queries.
kjetilk commentedon Nov 20, 2018
@dmitrizagidulin you were talking about this, IIRC, care to voice an opinion?
dmitrizagidulin commentedon Nov 21, 2018
@kjetilk My thoughts on this are:
We should deprecate globbing. It was always a placeholder, until better querying came along.
Instead, we should focus on:
JornWildt commentedon Nov 21, 2018
The LDP paging spec's use of HTTP headers (link relations) for paging information seems like a better idea then using URL parameters. Cool.
But I don't see any way to specify the ordering? The spec has a way to show what ordering the server selected - but I cannot find a way for the client to specify it? Given that the Solid server has no way to know what values to order by, it doesn't help much.
JornWildt commentedon Nov 21, 2018
I also think globbing still has value. In example 13 (https://www.w3.org/2012/ldp/hg/ldp-paging.html#ldpc-ex-ordering-nopaging) the LDP paging spec spec shows the content of a container - but here it includes (some? all?) statements from the container items ... but the Solid server only returns a few file system details about the container items. If I want the full resource content of the items, I need to use globbing.
melvincarvalho commentedon Nov 28, 2018
-1 on this. It's in use, and that kind of action is the sort of thing people moan about for years. Would not be a good advert for the dev team.
melvincarvalho commentedon Nov 28, 2018
That's not true at all. Do you have any reference to back this up?
RubenVerborgh commentedon Nov 28, 2018
melvincarvalho commentedon Nov 28, 2018
In this case the desired functionality is to get all the triples in a container. LDPC (aka folders) have a special role in solid. What you describe is more generic and also useful.
Glad to hear this!