PostgreSQL has excellent time series capabilities. It can load millions of rows per second, efficiently scan by time range, build rollup tables, has expressive SQL with excellent support for time (timezones, ranges, timestamps, intervals, conversion, etc.), it can combine multiple indexes to query large volumes of time series data quickly, it can do sampling, and it can expire data efficiently through partitioning. Ok, it's not entirely ootb. To make it work nicely you may need extensions like pg_partman to automate partitioning and Citus to scale out, but once you do you have a time series database that's faster and more powerful than anything else on the market.