Ok ... you know PostgreSQL supports hash tables in shared memory, right? PostgreSQL could in theory share those if we wanted to. The issue is just that coding anything which uses shared memory is a lot of work.
Additionally the reasons PostgreSQL does not offer Clickhouse performance has very little to do with parallelism. PostgreSQL plans to move to threading but the efforts around imporving OLAP performance are almost entirely unrelated.
Additionally the reasons PostgreSQL does not offer Clickhouse performance has very little to do with parallelism. PostgreSQL plans to move to threading but the efforts around imporving OLAP performance are almost entirely unrelated.