Save Subset of MongoDB Collection to Another Collection

Question

I have a set like so

{date: 20120101}
{date: 20120103}
{date: 20120104}
{date: 20120005}
{date: 20120105}

How do I save a subset of those d

Answer 1

There's no direct equivalent of SQL's insert into ... select from ....

You have to take care of it yourself. Fetch documents of interest and save them to another collection.

You can do it in the shell, but I'd use a small external script in Ruby. Something like this:

require 'mongo'

db = Mongo::Connection.new.db('mydb')

source = db.collection('source_collection')
target = db.collection('target_collection')

source.find(date: "20120105").each do |doc|
  target.insert doc
end