I'm trying to pull nested documents from a field of type array called " workers "  that is part of each document of a collection named "production_units", matching the condition that the nested document shouldn't contain 'worker_number' field. In fact I have a nested document which I need to get rid of, and it is structured as:   {name: "'WORKER EXAMPLE" }   In order to accomplish that, I used the operator $exists for the match. So this is what I used for performing the update:   db.production_units.update({}, {$pull: {workers: {worker_number: {$exists: false }}}}, {multi: true }) However it returned the following result: WriteResult({ "nMatched" : 30, "nUpserted" : 0, "nModified" : 0 })   Which means that no nested document was matched for $pull. Yet, I tried an alternative command using a hack {$not: {$type: 16} in order to perform something alternative to {$exists: false} for the match, but it worked using the following update syntax:   db.production_units.update({}, {$pull: {workers: {worker_number: {$not: {$type: 16}}}}}, {multi: true }) Resulting in the following output: WriteResult({ "nMatched" : 30, "nUpserted" : 0, "nModified" : 16 })   And afterwards, I realized that the nested document I wanted to delete, was removed.