Defining OLAP or OLTP on table level in Oracle/postgres/SQLserver

Usually companies have separate databases for OLTP and OLAP (Row stores and column stores) where data is loaded through ETL jobs to another database for analytical processing. I am particularly interested to know if there is any way we can define which tables or objects to store for OLAP and which tables or objects to store for OLTP queries in any RDBMS like oracle or postgres on any level of granularity in the same database.