If the query planner selects an index, the explain result includes a IXSCAN stage. IXSCAN means that now MongoDB doesn't need to do a collection scan but an index can be used to find the documents. I'm attempting to grep through some Mongo logs in an attempt to find slow operations that I need to optimize. I guess MongoDB can do index seek and index scan ? Yes MongoDB can do index seek and index scan, but it can do both during one fetch. Notes: the IXSCAN stands for Index Scan.