[limit per resource] implementation experience and/or concerns?

(just looking to get a bit of background discussion in advance of 
tuesday, to save time on the teleconference)

http://www.w3.org/2009/sparql/wiki/Feature:LimitPerResource

LIMIT, in SPARQL, normally just limits the total number of results 
returned. Combined with DISTINCT, it limits the total number of distinct 
tuples returned. Combined with an aggregate/grouping extension, it can 
limit the total number of groups returned.

But there's no way to limit based on certain variable(s) while allowing 
multiple rows per limiting variable. That's what limit per resource is 
about.

The wiki page has some good use cases.

I must say: while this is a problem I have come up against personally in 
the past, this is not a proposed solution that I was familiar with. 
Which is my main concern: while this seems like a fairly straightforward 
extension to SPARQL, it's not implemented anywhere that I know of.

So a few questions:

1/ does anyone implement this in SPARQL?

2/ does anyone implement this elsewhere (e.g. in SQL)?

3/ on the surface, are there any implementation, specification, or other 
concerns about this feature?


Lee

Received on Friday, 17 April 2009 04:34:52 UTC