Slow query when using SERVICE keyword
Here is a fast query:
time tracker3 sparql -q "SELECT
?song
WHERE {
?song a nmm:MusicPiece ;
nie:isStoredAs ?as .
}" --dbus-service org.freedesktop.Tracker3.Miner.Files > /dev/null
real 0m0,071s
user 0m0,024s
sys 0m0,004s
Now I add the SERVICE
keyword to the above query, and it gets really slow.
time tracker3 sparql -q "SELECT
?song
WHERE {
?song a nmm:MusicPiece ;
nie:isStoredAs ?as .
SERVICE <dbus:org.freedesktop.Tracker3.Miner.Files> {
GRAPH tracker:Audio {
SELECT
?song
WHERE {
?song a nmm:MusicPiece ;
}
}
}
}" --dbus-service org.freedesktop.Tracker3.Miner.Files > /dev/null
real 0m20,954s
user 0m0,020s
sys 0m0,010s
Why is this?