Single response vs. partial response with link to more data

[Casey OHara]

We are trying to implement a FHIR app in Cerner, that has also been used in EPIC.

The app is a longitudinal patient summary to provide a single location to obtain an overview of the patient's history and present conditions.

In EPIC all encounters are returned in a single response, medications in a single response, etc. However, we are seeing in Cerner that about 10 encounters are returned in a response with a link to the next 10, etc. This is the same for meds, problems, documents, etc. As a result the application is not performant in Cerner.

Is there a way to obtain a single response with all data for a specific data type (encounter, problem, medications, documents, etc.)? 

[Aaron McGinn (Oracle Cerner)]

For certain resources, such as Encounter [1], we support the _count [2] parameter defined by HL7. You will need to check the documentation for each resource you are consuming as to if it supports this search parameter.

[1] https://fhir.cerner.com/millennium/r4/base/management/encounter/#parameters

[2] https://hl7.org/fhir/r4/search.html#count

-Aaron (Oracle Cerner)

[Casey OHara]

Thank you Aaron.  We will look into using the _count parameter.  Is there is limit that is allowed by Oracle Cerner?  For example, if I were to choose a _count of 999 for encounter, will I only receive 500 with a link to the next page of 500?  

[Aaron McGinn (Oracle Cerner)]

It will be different per-resource some resources have a limit (i.e. 100) that if a number is provided above that, the limit will be used instead. These individual defaults/limits are not published, since they can/have changed as individual workflow improvements have been made. These limits are determined by internal testing to provide a reasonable response time based on the number of entities returned for a request.

-Aaron (Oracle Cerner)