Working on a new project which has the requirement to use 7 databases. Arguing performance, stability, optimization is easier implemented.

While I don't agree I'm having trouble collecting good arguments to use a single database. (While the 7 databases splits the tables in logical domains)

One argument I have so far is data integrity (can't us foreign keys between databases).

What are good pros/cons for using a single or multiple databases?

[summary so far]

Arguments:

• Losing data itegrity (can't use foreign key over databases)

• Losing restore integrity.

• Gaining complexity (db user/roles)

• Small odds server/database will go down.

Solutions:

• Use schemas to seperate domains.

• POC: Use dummy data to proof point in 7/1 db's execution plans