I'm building an application that monitors a public map for changes. When I detect an update via dataLastEditDate, I query the layer for its features.
Intermittently, both returnCountOnly=true and full feature queries return 0 results for layers that definitely have data.
What I've observed:
- returnCountOnly=true sometimes returns {"count": 0} for layers that are not empty
- Full feature queries (where=1=1&outFields=*&f=json) sometimes return 0 features even when the count endpoint returns the correct count
- The issue is transient — retrying after a few seconds usually recovers the data
- I'm using POST requests with cacheHint=true and cache-busting timestamps
My questions:
- When a hosted feature service exceeds its request unit quota, is it expected for queries to silently return {"count": 0} or empty feature arrays instead of a 429 error? The empty response is indistinguishable from a legitimately empty layer.
- Does the query format affect reliability under load? Would f=pbf or f=geojson be more resilient than f=json?
- Are returnCountOnly and full feature queries served from different infrastructure? That would explain why count succeeds but features fail.
Any insight appreciated. My current workaround is retry logic with backoff, but I'd like to understand the underlying behavior.
