Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{_id:1,date:"1948-12-08 00:00:00.000"},{_id:2,date:"1970-01-01"}]
Query
db.collection.aggregate([{"$addFields":{"date":{"$arrayElemAt":[{"$split":["$date"," "]},0]}}}])
Result