The following query operators all require that the field they operate on be present in the document, and are thus compatible with {$exists: true}:
- $exists
- $type
- $mod
- $regex
- $geoIntersects
- $geoWithin
- $elemMatch
- $size
The following query operators allow using null to match documents where the field is omitted from the document, and are only compatible with {$exists: true} if the value is non-null:
- $eq
- $gt
- $gte
- $lt
- $lte
- $in
The following query operators allow using non-null values to match documents where the field is omitted from the document, and are only compatible with {$exists: true} if the value is null:
- $ne
- $nin