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Understanding Oracle’s data consistency mechanisms is key to ensuring reliable database operations. Even after a commit, changes may not be immediately written to the datafiles due to Oracle’s DBWn process. Instead, Oracle relies on the Online Redo Log to recover committed transactions in the event of a crash. Learn why redo logs are essential for data integrity and how undo and read consistency maintain accurate query results across sessions.

Learn the fundamentals of Oracle Database architecture in this beginner-friendly guide. Discover how Oracle instances work, including essential memory structures like SGA, PGA, UGA, and key background processes such as PMON, SMON, DBW, and LGWR. Perfect for new DBAs, developers, and anyone starting their journey into Oracle databases.

In this post we will look at the Online Redo Log which consists of physical files that store redo records, capturing changes made to the database. These records are crucial for the recovery process, as they facilitate “roll forward” of committed changes and “roll back” of uncommitted ones.

In this back-to-basics we go into what a database instance is. We view key components like the System Global Area (SGA) and background processes such as PMON and DBWn that ensure efficient memory management and data integrity. Understanding instances is crucial for database performance and administration.

A small blog post on what I will be looking forward at OCW 24 around Multicloud