BigQuery streaming ingest also uses in-memory buffering into BigTable until it's written to disk, just like Cassandra with memtables flushed into on-disk SSTables.
Citus is more manual work than MemSQL and doesnt support columnstores native, although you can use it with their cstore extension to get both. It's just a different design giving you a postgres database that automatically shards vs MemSQL's many optimizations around HA, replication, and very fast analytics performance.
Try the features page: http://www.memsql.com/features/
This article had a nice overview. Somewhat outdated but mostly still up to date. https://lnkd.in/g4anCf5
I’ll say it seems precarious to me to mix and match row store in memory data with a columnar store. Is it never a performance issue to have these two systems potentially in contention with one another for resources?
Version 6 is even faster, you can try out the beta: http://www1.memsql.com/beta-6.3-features.html
Can you share some docs with me around how citus is more OLTP based? Looking to be educated.