Oracle undo, blocks read, and performance

Today we talk about the purpose of Oracle undo and give a demonstration of its use and little bit of what Oracle is doing under the covers.  We also show how query performance can be affected by what else is going on in the database. In the last post on transactions,...

What is an Oracle transaction?

In this post we’ll do a short discussion about Oracle transactions, and a simple demonstration of the principles discussed. The term transaction in Oracle means to take some data in the database from one consistent state to another.  The work done in a transaction by...

What happens in an Oracle database startup?

In this post we’ll walk through the stages of an Oracle database startup and a few important notes along the way. At the simplest level there are three main stages of an Oracle startup. NO MOUNT:  The database instance is started.  The spfile or parameter file is...