Database Arcitecture

Database Arcitecture

Database architecture is divided in to 2

   1.Database instance
   2.Database


1.Database Instance :

-->Database Instance Structure. When an instance is started, Oracle Database allocates a memory area
called the system global area (SGA) and starts one or more background processes. The SGA serves various
purposes, including the following:

-->The combination of both SGA and background process is called the database instance .

2.Database:  

              It is classified into 2 layers
                a. logical layer
                b. Physical layer

a)Logical layer - (Tables,Views,Index,Synonyms , Sequences)
b)Physical layer - ( DBfiles --> Filesystem --> Operating system --> Disk)