Mongo remove last documents

Question

I would like to know how to delete, for example, the last 100 documents inserted in my collection.

How is it possible from the shell?

Answer 1

You should be able to use the _id to sort on last inserted, as outlined in the answer here:

db.coll.find().sort({_id:-1}).limit(100);

It looks like using limit on the standard mongo remove operation isn't supported though, so you might use something like this to delete the 100 documents:

for(i=0;i<100;i++) {
    db.coll.findAndModify({query :{}, sort: {"_id" : -1}, remove:true})
}

See the docs for more on findAndModify.