FUNDAMENTALS OF COMPUTER

Detailed explanation-1: -An instance in a database is a combination of the program and memory used to access metadata and application data stored in physical files on a server. For example, whenever you log into a database, each login session is an instance.

Detailed explanation-2: -The five major components of a database are hardware, software, data, procedure, and database access language.

Detailed explanation-3: -For example, lets say we have a single table student in the database, today the table has 100 records, so today the instance of the database has 100 records. Lets say we are going to add another 100 records in this table by tomorrow so the instance of database tomorrow will have 200 records in table.

Detailed explanation-4: -All components such as Log Writer (LGWR), DB Writer (DBWR), Checkpoint (CKPT), Recovery Process (RECO), Lock Process (LCKn), Archive Process (ARCH), System Monitor (SMON), and Program Monitor (PMON) are referred to as an Oracle Background processes.