How to remove a field completely from a MongoDB document?

Question

{      name: 'book',     tags: {         words: ['abc','123'],         lat: 33,         long: 22     } } 

Suppose this is a document. How do I remove "words" completely from all the documents in this collection? I want all documents to be without "words":

 {       name: 'book',      tags: {          lat: 33,          long: 22      } } 

Answer 1

Try this: If your collection was 'example'

db.example.update({}, {$unset: {words:1}}, false, true); 

Refer this:

http://www.mongodb.org/display/DOCS/Updating#Updating-%24unset

UPDATE:

The above link no longer covers '$unset'ing. Be sure to add {multi: true} if you want to remove this field from all of the documents in the collection; otherwise, it will only remove it from the first document it finds that matches. See this for updated documentation:

https://docs.mongodb.com/manual/reference/operator/update/unset/

Example:

db.example.update({}, {$unset: {words:1}} , {multi: true});