Join Two Collections In Mongodb Using Python


How do I merge two MongoDB collections?

Specify either:

1. The collection name as a string to output to a collection in the same database where the aggregation is run. For example: into: "myOutput"

2. The database and collection name in a document to output to a collection in the specified database. For example: into: { db:"myDB", coll:"myOutput" }

$merge (aggregation) — MongoDB Manual > manual > reference > operator > aggregation > merge

Can we join 2 collections in MongoDB?

11 Answers. MongoDB 3.2 now allows one to combine data from multiple collections into one through the $lookup aggregation stage. As a practical example, lets say that you have data about books split into two different collections.

MongoDB: Combine data from multiple collections into > questions > mongodb-combine-data-from-multiple-co...

Can you do joins in MongoDB?

If we were using a relational database, we could perform a join on users and stores, and get all our objects in a single query. But MongoDB does not support joins and so, at times, requires bit of denormalization.

How do I perform the SQL Join equivalent in MongoDB? > questions > how-do-i-perform-the-sql-join-equivalent...

How do I link two documents in MongoDB?

MongoDB applications use one of two methods for relating documents:

1. Manual references where you save the _id field of one document in another document as a reference. ...

2. DBRefs are references from one document to another using the value of the first document's _id field, collection name, and, optionally, its database name.

Database References — MongoDB Manual > manual > reference > database-references

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