Oracle database is mainly formed of two major components – oracle instance, oracle database. When exploring the oracle database we see – physical storage structures and logical storage structures. We’ll be discussing information on physical storage structures.
What is a physical storage structure?
Physical storage structures also called as physical database structures are the set of files that store data/information
How do you create physical storage structures?
Physical storage structures are created when we install a new version of oracle software and create an oracle database. When using OUI (Oracle Universal Installer) to install a new version of oracle software we’ll be prompted and asked if we need to create a new database as a part of software installation process. If we click yes database is created. It is during this process, the physical storage structures are created. If not we can create database later on using :
1) dbca – GUI to create a database
2) CREATE DATABASE command
In either of the above mentioned database creation processes, physical storage structures are created.
What files are included in the physical storage structures?
Three major files form part of these physical storage structures. They are :
1) Data files – Physical files which store database data. There can be one or more datafiles to store information
2) Control Files – It stores metadata information on physical structure of database including database name, names and location of database files. Loss of control files will lead to system crash. Control files are multiplexed to prevent loss
3) Online Redo Log Files – They play a major role in transaction management. Data consistency is a major factor which is achieved using concept of redo records. Entries of redo records are updated live in online redo log files. They can be archived as archived redo log files for system recovery if needed