Filtering & Sorting on a container

[ghanemabdo]

There should be a way for clients to run sorting/filtering operations (partial Globing) on resources under a container (not using SPARQL). Something similar to WHERE & SORT BY clauses in SQL. I can think of several use cases such as a twitter-like app that should display the recent x posts and gradually loads batches of x posts, displaying a paginated table ... etc

I have two approaches in mind now:

1. Client reponsibility: the client is responsible for naming resources in a container in a sequential way (timestamp or auto increment index) and maintains these indexes to allow filtering/sorting via normal LDP requests.
2. Server responsibility: client states the filtering/sorting along with a globing request and the server does the filtering/sorting and responds by the results.

This is what on top of my mind. What do you think ... any suggestions?

[bblfish]

One simple way to do that is to support SEARCH verb on containers. See issue 46: Document Query use cases

[melvincarvalho]

It's an interesting frontier. One way is to place data into a well organized folder structure, which I think can take you a long way.

Query is quite a large implementation burden, and would take time to standardize and roll out.

The operations I think that are common are :

• get items by time e.g. by day
• limit number of items e.g. last 50
• get items from a certain id e.g. pagination

Should we just use full SPARQL here, I wonder? Maybe a lite version could help gain adoption in the interim, but that's a tough one to judge.

[melvincarvalho]

Perhaps possibly solid needs a pagination spec for large containers, something I think LDP was working.

[sandhawke]

Pagination only makes sense when the items are sorted in such an order that clients usually only want the first few, like tweets. We're much better off with a query system.

[ebporter]

Pagination makes sense in lots of cases:

• When you think you can find something in the first page of results of a query, but you don't find it, so you keep looking.
• When items are sorted, but you still want to browse through the full extent of them
• When you don't know what you're looking for, but a sort order at least allows you to comb through items against some kind of criteria
• In order to support poor Internet connections... "the first few" might mean 5 or 50, depending on what the items are and how much it costs to load each one Anyway, pagination seems useful, though maybe this is all client side optimization.