How to order by in DynamoDB with the AWS SDK?

Question

Currently, my range value is a BigDecimal attained by Time.now.to_f, and I want to retrieve all the documents of a user, like so:

table = dynamo_db.tables['some_table']
table.load_schema
docs = table.items.where(:user_id => user_id).select.map {|i| i.attributes}

The docs is ordered in the range value descending.

Answer 1

After digging into the SDK source code, I was able to find this little useful nugget for the method AWS::DynamoDB::ItemCollection#query

  # @option [Boolean] :scan_index_forward (true) Specifies which
  #   order records will be returned.  Defaults to returning them
  #   in ascending range key order.  Pass false to reverse this.

Since my user_id is the hash value, I was able to revise my query to:

docs = table.items.query(:hash_value => user_id, :scan_index_forward => false).select.map {|i| i.attributes}