mongod 3.0.2, sharded collection with 2.72B documents.

running a query with db.col.explain("executionStats").find(querydoc).sort(sortdoc) does not return any data even if wait hours. db.col.find(querydoc).sort(sortdoc) would work after a few seconds. Similarly, if you do a :

db.col.find(querydoc).sort(sortdoc).explain() , you will get results after a few seconds, where db.col.find(querydoc).sort(sortdoc).explain("executionStats") just hangs.