On 4/24/17 5:28 AM, Miguel Paraz wrote:
I'm referring to a query like this, based on the Wikidata cats example:
?item wdt:P31 wd:Q146 .
?crash rdfs:label ?_crashLabel
I think you misunderstand the query. What this query says is: Give me
all bindings where ?item is part of triple such that it has predicate
wdt:P31 and object wd:Q146, and ?crash and ?_crashLabel are such that
they are linked by rdfs:label predicate. The latter probably has a lot
of bindings if you have loaded wikidata dump, since the data has a lot
of triples with predicate rdfs:label. So while trying to process all
these bindings, you get OOM.
In general, I'd recommend always putting limit on a query when you're
trying to compose it. If you don't need it, remove it as the last step,
but until you're sure your query means what you think it means, use
limit, it'll save you time and frustration and CPU resources :)
Could Blazegraph prevent this query from even
There's no reason to prevent this query from starting, it's a completely
legitimate query, just most likely not doing what you thought it's doing.