Question

I have tons of data in my database. and i have so many duplicates in it. I want to remove all these duplicates and keep only one data from it,

For example i have data like this in my login object

id name

123 abc

124 abc

125 abc

126 abc

127 pqr

128 pqs

i want to keep only one user whose name is ‘abc’ and remove all the other users whose name is ‘abc’
How can i achieve it in mongodb
thanks in advance

Answer 1

One method is to actually create a unique index on the users name and give it an option to dropDups: http://docs.mongodb.org/manual/core/indexes/#drop-duplicates

So for your example:

db.user.ensureIndex({name:1},{unique:1,dropDups:true})

Would create a unique index on the name that will drop all other duplicates.

Of course the double benefit of this is that you now have a unique index on the name ensuring that you don’t get duplicates again.

You can also do this via clent side but it is likely to be slower than doing it by building an index.