That’s assuming you’ll constantly be doing reads of only the last 10 seconds of data. If that’s the case, this isn’t the database you should use (or even the data model). If you are tracking vehicles or IoT devices or whatnot the reason you’d do those kinds of reads is because you want to know where things are right now, so using a data store optimized for knowing where they used to be at some arbitrary point in time is not the right tool. If you want to keep track of the latest state all the time store it in a another data structure instead.

Once you flush your input buffer, everything becomes sequential so after your 10 second window you no longer have this problem. And even for the latest 10 seconds reading an index won’t be terrible as far as performance because your input buffer is relatively small (compared to your huge dataset).