How to select random DBPedia nodes from SPARQL?

In SPARQL 1.1 you can do:

SELECT ?s
WHERE {
  ?s ?p ?o
}
ORDER BY RAND()
LIMIT 10

I don't know offhand how many store will optimise, or even implement this yet though.

[see comment below, this doesn't quite work]

An alternative is:

SELECT (SAMPLE(?s) AS ?ss)
WHERE { ?s ?p ?o }
GROUP BY ?s

But I'd think that's even less likely to be optimised.

bif:rnd is not SPARQL standard and therefore not portable to any SPARQL endpoint. You can use LIMIT , ORDER and OFFSET to simulate a random sample with a standard query. Something like ...

SELECT * WHERE { ?s ?p ?o } 
ORDER BY ?s OFFSET $some_random_number$ LIMIT 10

Where some_random_number is a number that is generated by your application. This should avoid the caching problem but this query is anyway quite expensive and I don't know if public endpoints will support it.

Try to avoid completely open patterns like ?s ?p ?o and your query will be much more efficient.