We are using Google healthcare FHIR store v1 with node.js client (googleapi). Google Cloud platform API docs for v1beta1 (but not v1) mentioned $lastn, and the npm package (googleapi) only has the ObservationLastn() function when initialized with version="v1beta1", not with "v1". Is Google Healthcare dropping $lastn support in v1 (and later)?
We were able to make the $lastn work on v1 FHIR store with the googleapi client initialized with "v1beta1", but the 1000 resources matches (not unique code) is too strict. Is it something configurable?
APIs are promoted to v1 based on the maturity of the feature, as well as customer demand. I recommend you use the "Send Feedback" link on the Observation-lastn documentation page so that the team knows you are interested in seeing this feature go to v1.
As for the 1000 resource limit, this is not configurable as it required to keep the performance acceptable. Feel free to mention your use case if you file feedback. But in the meantime, if you need to process more than 1000 search results I suggest you use the Search API and do the paging and post-processing yourself.