
Distributed DBMS Architecture
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A set of global external schemas
A global conceptual schema (GCS)
A fragmentation schema and allocation schema
A set of schemas for each local DBMS, conforming to the ANSI–SPARC three-level ar-
chitecture.
Global external schema – In a distributed system, user applications and user accesses to the dis-
tributed database are represented by a number of global external schemas. This is the topmost level
in the reference architecture of a distributed DBMS. This level describes the part of the distributed
database that is relevant to different users.
Global conceptual schema – The GCS represents the logical description ...