Avoiding RI (in part due to poor FK support depending on version / storage engine), designs that avoid simple schema changes because they can't be done online,

Avoiding RI (in part due to poor FK support depending on version / storage engine), designs that avoid simple schema changes because they can't be done online, point version migration difficulties. Consider unsupported SQL constructs from other engines (CTEs, window functions, better join and subquery support), and the effort and mess to accomplish what should be straightforward tasks generates SQL hate. Some NOSQL projects have merit as they provide mechanisms for working with data structures that do not map well to rows and columns. However, difficulties faced with MySQL have also pushed some projects to use equivalently broken data storage technology, when a "better" RDBMS would be more appropriate.