From
The From clause is in essence a filter on resource type.
from Patient select id, name.family, name.given
The above statement effectively selects all patient records in scope, which could be all patients of the entire server.
Bandwidth
When requesting data from a FHIR server, the from
clause is also mapped to a search query to reduce bandwith and increase performance, like this:
using 'https://vonk.fire.ly' from Patient select ...
The from Patient
clause here is translated to a FHIR search request URL to the FHIR server: http://server.org/fhir/Patient
.