Is it possible to do a $lookup aggregation between two databases in Mongodb?
Is it possible to do a $lookup aggregation between two databases in Mongodb?
It is not possible to query using lookup in two different db's.$lookup in mongodb supports Performs a left outer join to an unsharded collection in the same database.
{ $lookup: { from: <collection to join>, localField: <field from the input documents>, foreignField: <field from the documents of the "from" collection>, as: <output array field> }}We can use getSibling("dbname") to query another db from one db
db.getSiblingDB('test').foo.find()Reference - MongoDB cross database query
Yes just read the following mongodb doc:
In Atlas Data Lake, $lookup can be used to perform a join of collections from different databases.
https://docs.mongodb.com/datalake/reference/pipeline/lookup-stage