Remove documents in batches

batchRemove.js

// Note: Ensure there's an existing index, e.g.:
//   db.assets.ensureIndex({ assetExpiration: 1 })

// Since remove() doesn't support limit(), we can't do the following directly:
//   db.assets.remove({ assetExpiration: { $lt: newDate() } }).limit(batchSize)
// So we do the following instead:

batchSize = 100
removeMe  = []

db.assets.find({ assetExpiration: { $lt: newDate() } }, { _id: 1 }).
   limit(batchSize).
   forEach(function(doc) { removeMe.push(doc._id) })

db.assets.remove({ _id: { $in: removeMe } })