If your stream has Persist last known value set to True, you will be able to query the most recent datapoint on that stream, regardless of when it was ingested.
You can configure the Persist last known value setting for any data stream in Formant by going to Settings >> Streams and clicking on the relevant stream.
You can see an example of how to query the last known value of a range of streams in the following example: GitHub: query_stream_latest.py.
In the file above, you'll see how to query the last known value of:
- all streams which ingested data within a certain time range,
- all streams matching a given name, and
- all streams matching a given tag.