Frank installed her app. It took 45 seconds. It launched. It created a database inside his %USERPROFILE% . It just worked.
LocalDB wasn't a toy. It was a full —with the same TRANCOUNT , the same sp_who2 , the same transaction isolation levels—but wearing a stealth suit. It ran as a child process of her application. It communicated over named pipes , not TCP/IP (though you could enable that). It even supported multiple instances : one for development, one for testing, one for that legacy reporting tool she was scared to touch. microsoft sql server express localdb
Later, she learned the truth about her new friend. Frank installed her app
She ran integration tests. They ran in 800ms. She ran unit tests with a fresh database. sqllocaldb stop Contoso followed by sqllocaldb delete Contoso wiped everything clean in a millisecond. It created a database inside his %USERPROFILE%
Her first customer was a bakery owner named Frank, running Windows 10 Home on a 2014 Dell Inspiron with 4GB of RAM.