When High Availability is on(I am using the column store tables), How fast is the data replicated to its availability pair? Is it eventual or immediate?
If you are using redundancy 2 for high availability, MemSQL can replicate partitions between nodes synchronously (immediate) or asynchronously (eventual). In 6.8, asynchronous replication is a lot faster than synchronous replication. So most people use asynchronous replication unless they really need immediate consistency. In 7.0, synchronous replication will be almost as fast as asynchronous replication (typically within 15 to 25%). 7.0 synchronous replication can be about 100 times faster than synchronous replication compared with 6.8 and earlier. So we expect most people will turn on synchronous replication after 7.0 ships. You can try the new replication model in 7.0 beta 1 (https://www.memsql.com/7-beta-1) if you are interested.