[vlmutolo]

The commenter you're responding to isn't saying that it's literally impossible to retrieve a single point without doing a full scan of the data, but rather that it's not the top priority of these data structures to support queries for individual points.

The GP comment even says:

> Time series queries consists mainly of "get me all the data points of a time series reported between timestamps A and B"

which seems exactly like what you mentioned with "$now-$period".

These kinds of data structures, often found in OLAP databases, assume that point queries will be less common, and they accept a bit higher latencies for those queries. But those latencies are still fairly small.