Situation: half of a million of an indexed by Lucene documents(emails actually), searching for emails by sender/receiver and some text.
If to put text filter in the start of SPARQL query it executes once but in a case of very common words here are a lot of results(100 000+) that leads to poor performance, limiting results count may and up with missed results.
If to put text search as the last condition it executes once per each already found subject. That's completely OK but text search completely ignores subject URI.
I found two methods in TextQueryPF class: variableSubject(...) for the first case, and concreteSubject(...) for the second one.
The question is: why can't subject URI be used as a constraint in the text search?