In the previous chapter, we discussed top-down distributed database design, which is suitable for tightly integrated, homogeneous distributed DBMSs. In this chapter,
we focus on bottom-up design that is appropriate in multidatabase systems. In this
case, a number of databases already exist, and the design task involves integrating
them into one database. The starting point of bottom-up design is the individual local
conceptual schemas. The process consists of integrating local databases with their
(local) schemas into a global database with its global conceptual schema (GCS) (also
called the mediated schema).
