Adds a new stream called SelectStream which can be used for two purpose.
1. Limit the set of fields included in an outgoing tuple to remove unwanted fields
2. Provide aliases for fields. With this it acts as an alternative to the CloudSolrStream's 'aliases' option.
For example, in a simple case
This can also be used as part of complex expressions to help keep track of what is being worked on. This is particularly useful when merging/joining multiple collections which share field names. For example, the following results in a set of tuples including only the fields id, left.ident, and right.ident even though the total set of fields required to perform the search and join is much larger than just those three fields.
This depends on