Regarding MemSQL: - we have just released v2.5 with full support for JSON and online ALTER TABLE across cluster - MemSQL performs great on both OLAP and OLTP -

Regarding MemSQL: - we have just released v2.5 with full support for JSON and online ALTER TABLE across cluster - MemSQL performs great on both OLAP and OLTP - it scales well: we have several hundred node cluster in production at Zynga - license cost for startups is $1