The environment of database is said to be instance. A database instance or an ‘instance’ is made up of the background processes needed by the database software. These processes usually include a process monitor, session monitor, lock monitor, etc. They will vary from database vendor to database vendor.
A database instance (Server) is a set of memory structure and background processes that access a set of database files. The process can be shared by all users. The memory structure that are used to store most queried data from database. This helps up to improve database performance by decreasing the amount of I/O performed against data file.
It includes RDBMS software, table structure, stored procedures and other functions. It is normally used when administrators tend to describe multiple instances of the same database. It is also called as environment in technical terms. You can better understand its workings with the help of an example. The example is of an organization that has an employee database. This database will have three instances, which are
• Production That is used for storing live data
• pre-production which is used to test new functionality prior to release for production
• Development which is used by database developers in order to create new functionality