SensorThings $orderBy=phenomenonTime desc is ignored

[daniel-slaugh]

Steps to Reproduce

Attempt to get the latest observation from a datastream:

https://hydroserver.waterrights.utah.gov/api/sensorthings/v1.1/Datastreams?$select=id,name,properties&$expand=Thing($select=id,name,properties),Observations($select=result,phenomenonTime;$orderby=phenomenonTime%20desc;$top=1)&$top=1000

Expected Behavior

This should get the latest observation from the datastream.

Actual Behavior

Instead the first observation is returned.

Any additional comments?

I was able to get the latest observation by also including Datastream/id, but the first request with only the phenomenonTime ordering should work. It seems that HydroServer requires both before it honors phenomenonTime.

https://hydroserver.waterrights.utah.gov/api/sensorthings/v1.1/Datastreams?$select=id,name,properties&$expand=Thing($select=id,name,properties),Observations($select=result,phenomenonTime;$orderby=Datastream/id%20asc,phenomenonTime%20desc;$top=1)&$top=1000

[kjlippold]

This is being caused by a guard from our old STA implementation we had in place to prevent sorting of the entire observations table on non-indexed fields, but it's being applied even when other filters are in place. I'm going to remove the guard for now. We may run into performance issues on some sorting queries on some instances, but we can reapply the guard more narrowly later if needed.