logs, spans and metrics are stored as time-stamped stuff. sure simple fixed-width columnar storage is faster, and makes sense to special case for numbers (add downsampling and aggregations, and histogram maintenance and whatnot), but any write-optimized storage engine can handle this, it's not the hard part (basically LevelDB, and if there's need for scaling out it'll look like Cassandra, Aerospike, ScyllaDB, or ClickHouse ... see also https://docs.greptime.com/user-guide/concepts/data-model/ and specialized storage engines https://docs.greptime.com/reference/about-greptimedb-engines... )