What's the fastest way to copy a collection within the same database?

Question

I want to copy a collection within the same database and give it a different name - basically take a snapshot.

What\'s the best way to do this? Is

Answer 1

First option (Using mongo dump)

1. Get a dump from collection

   mongodump -d db -c source_collection

2. Restore from collection

   mongorestore -d db -c target_collection dir=dump/db_name/source_collection.bson

Second Option

1. Running aggregate

   db.getCollection('source_collection').aggregate([ { $match: {"emailAddress" : "apitester@mailinator.com"} }, { $out: "target_collection" } ])

Third Option (Slowest)

1. Running a through for loop

   db.getCollection('source_collection').find().forEach(function(docs){ db.getCollection('target_collection').insert(docs); }) print("Rolleback Completed!");

Answer 2

Note: Read the answer Updates, they are important!

---

The most simple & efficient way is by using copyTo(), so you can use:

db.source.copyTo("target"); 

& if "target" doesn't exist, it will be created

-- Update --

According to CopyTo Documentation, Because copyTo() uses eval internally, the copy operations will block all other operations on the mongod instance. So it shouldn't be used on production environment.

-- Update --

Because CopyTo() uses eval() internally & eval() is deprecated since version 3.0, so CopyTo() is also deprecated since version 3.0.

Answer 3

This is my implementation in python (pymongo):

def copy_collection(client, from_db, from_coll, to_db=None, to_coll=None):
    to_db = from_db if to_db is None else to_db
    to_coll = from_coll if to_coll is None else to_coll
    assert (to_db != from_db or to_coll != from_coll), "Copy Error: Source and destination can't be same!"
    documents = client[from_db][from_coll].find()
    client[to_db][to_coll].insert_many([d for d in documents])

Answer 4

The fastest way is db.collection.copyTo().

Note that it is deprecated since version 3.0.

Answer 5

You can use the copyDatabase function in the mongo shell:

http://docs.mongodb.org/manual/tutorial/copy-databases-between-instances/

Answer 6

You have a few options, but the fastest is:

mongodump -d db -c sourcecollection 
mongorestore -d db -c targetcollection --dir=dump/<db>/<sourcecollection.bson>

or

mongoexport -d db -c sourcecollection | mongoimport -d db -c targetcollection --drop

or in php:

`mongoexport -d db -c sourcecollection | mongoimport -d db -c targetcollection --drop`;

after that you have

mongo db < script.js

where, as shown in the mongo docs, script.js contains something like:

db.myoriginal.find().forEach( function(x){db.mycopy.insert(x)} );

The slowest (by an order of magnitude or more) way to copy a collection will be to use the native php driver - simply because of moving information around. But you could issue the above mongo query if you absolutely want to avoid cli calls using the db execute function.