I´m waiting for a compact data-structure such as RocksDB. I store TBs of data and MySQL and MyRocks are miles ahead on this department compared to Postgres. I prefer to run from sharding and distributed solutions for now.
I am curious what specifically makes RocksDB compact comparing to Postgress? How you decided it is more compact?
Simply by larger sizes of compressed blocks, which are limited to page size in Postgres, and by improving the data locality by sorting, which is inherent for LSM-trees.
But if you want higher compression, you need to consider column-oriented DBMS, such as ClickHouse[1]. They are unbeatable in terms of data compression.
[1] https://github.com/ClickHouse/ClickHouse
Disclaimer: I'm a developer of ClickHouse.