Have used RRDtool in the distant past. It's a fascinating project from a time when things were designed with hardware limitations in mind. https://oss.oetiker.ch/rrdtool/
RRDtool stores its data values in a circular buffer (or many buffers, at different resolutions) so performance is constant - it doesn't degrade over time. Also resource usage is constant. The price you pay is that older data is stored at coarser resolution. I assume it also made the data points fixed in time for performance reasons, which is fine in my opinion.
I don't know if there are modern integrations or reporting tools built on the database.
RRDtool stores its data values in a circular buffer (or many buffers, at different resolutions) so performance is constant - it doesn't degrade over time. Also resource usage is constant. The price you pay is that older data is stored at coarser resolution. I assume it also made the data points fixed in time for performance reasons, which is fine in my opinion.
I don't know if there are modern integrations or reporting tools built on the database.