Unreasonably slow MongoDB query, even though the query is simple and aligned to indexes

Question

I\'m running a MongoDB server (that\'s literally all it has running). The server has 64gb of RAM and 16 cores, plus 2TB of hard drive space to work with.

The Doc

Answer 1

Have you tried adding _id to your composite index. As you're using it as part of the query won't it still have to do a full table scan?