The mongo docs specify that you can specify a query hint for count queries using the following syntax:
db.orders.find(
{ ord_dt: { $gt: new Date('01/01/2012') }, status: "D" }
).hint( { status: 1 } ).count()
Can you do this using the mongo template? I have a Query object and am calling the withHint method. I then call mongoTemplate.count(query); However, I'm pretty sure it's not using the hint, though I'm not positive.
Sure, there are a few forms of this including going down to the basic driver, but assuming using your defined classes you can do:
Date date = new DateTime(2012,1,1,0,0).toDate();
Query query = new Query();
query.addCriteria(Criteria.where("ord_dt").gte(date));
query.addCriteria(Criteria.where("status").is("D"));
query.withHint("status_1");
long count = mongoOperation.count(query, Class);
So you basically build up a Query object and use that object passed to your operation, which is .count() in this case.
The "hint" here is the name of the index as a "string" name of the index to use on the collection. Probably something like "status_1" by default, but whatever the actual name is given.
mongoTemplate.find(query, Class).size() It blows up with the error planner returned error: bad hint, but if I run mongoTemplate.count(query, Class) it works fine. Maybe count doesn't use the planner, but to me it seems like it's not working.
Query object for spring-mongodb. It just calls the underlying driver method to do the same. I was going to point out originally that you should reverse the order of arguments to "help" the query optimizer understand what you mean without "forcing" the "hint" in the first place. Generally the optimizer should "sort it out" given which choice produces the "least matches", which means "optimal".