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