Multiple home-made Databases, Godis(akin Redis), HiSQL(akin MySQL), MemDB, DataGo(akin ETL) etc.
wx-chevalier/reinvent-sqldb
Multiple home-made Databases, Godis(akin Redis), HiSQL(akin MySQL), MemDB, DataGo(akin ETL) etc. Understanding DBs by Reinventing It.
JavaMIT