Oracle Database Storage Structures

Key Concepts

• Datafiles
• Control Files
• Redo Log Files

Datafiles

Datafiles are the physical files on disk where the actual data of the Oracle database is stored. Each tablespace in the database has one or more datafiles associated with it. These files are managed by the Oracle Database Management System (DBMS) and are essential for data persistence.

Imagine datafiles as individual bookshelves in a library. Each bookshelf (datafile) holds a collection of books (data), and together, they form the entire library (tablespace).

Control Files

Control files are critical components of the Oracle database that contain metadata about the database. This metadata includes information such as the database name, creation date, and the location of datafiles and redo log files. The control files are essential for the database to start and operate correctly.

Think of control files as the blueprint of a building. Just as a blueprint contains essential details about the structure, control files hold vital information about the database's configuration and state.

Redo Log Files

Redo log files are used to record all changes made to the database. These files are crucial for database recovery, as they allow the database to replay transactions in case of a failure. Redo log files are written sequentially and are typically stored in groups for redundancy.

Consider redo log files as a journal that records every action taken in a day. If something goes wrong, the journal (redo log files) can be used to reconstruct the day's events (transactions) and restore the state of the database.