avocado> db.full.select({ a : 1 });
{"a":1,"b":{"c":2},"_id":"134057:2165673"}
{"a":1,"b":{"c":1},"_id":"134057:1837993"}
{"a":1,"b":{"c":1,"d":1},"_id":"134057:2100137"}

avocado> db.full.select({ b : { c : 1 } });
{"a":1,"b":{"c":1},"_id":"134057:1837993"}

avocado> db.full.select({ "b.c" : 1 });
{"a":1,"b":{"c":1},"_id":"134057:1837993"}
{"a":1,"b":{"c":1,"d":1},"_id":"134057:2100137"}