[Dbpedia-discussion] SPARQL - Auto-completion

[<gia...@op...>]

Hi,

I would like to query DBPedia to build an auto-completion feature and I am
not able to figure out the best way to write the associated SPARQL.


Assuming that I would like to auto-complete 'cambri', this query should work:


SELECT ?s
WHERE {
  ?s rdfs:label ?label
  FILTER regex( str(?label), "^cambri", "i" )
}
ORDER BY ASC(?label)
LIMIT 5


The problem is that it is too slow and timeout. People have been suggesting to use the 
OpenLink Virtuoso built-in-function "contains" as it performs better than regex filters.

So, this query is better:


SELECT DISTINCT ?s
WHERE {
  ?s rdfs:label ?label
  FILTER (bif:contains(?label, 'cambrid'))
}
ORDER BY ASC(?label)
LIMIT 5


Unfortunatelly, it is sematically incorrect as I would like to find the resources starting with 'cambrid' and not 
simply containing 'cambrid'.


So, I though that combining the filter could do the trick - here, assuming that
combined filters are evaluated from left to right:


SELECT DISTINCT ?s
WHERE {
  ?s rdfs:label ?label
  FILTER (bif:contains(?label, 'cambrid') && regex( str(?label), "^cambrid", "i"))
}
ORDER BY ASC(?label)
LIMIT 5


This query returns an empty set.

Any idea about achieving such an auto-completion.


Thanks,
Gianny