Index does not work when using order().by() in Titan

Question

The Titan documentation says that:

Mixed indexes support ordering natively and efficiently. However, the property key used in the order().by() method must

Answer 1

You must supply a value to filter on for the indices to be used. Here:

g.V().order().by('prop1', incr)

you don't provide any filter, so Titan has to iterate all of V() and then applies the sort.

Here:

g.V().has('prop1').count()

you supply a indexed key but don't specify a value to filter on so it's still iterating all of V(). You could do:

g.V().has("prop1", textRegex(".*")).count()

In this case, you would fake Titan out a bit, but the query still could be slow anyway if that query returns a lot of results to iterate over.