Automatic Transaction Rollback

Join Lois Houston and Nikita Abraham as they discuss the Automatic Transaction Rollback feature with Senior Principal Database & MySQL Instructor, Bill Millar. Bill explains that in the 23ai release, transactions blocking other transactions can now be automatically rolled back, depending on certain parameters. Bill highlights the advantages of using automatic transaction rollback, which eliminates the time-consuming process of manually terminating blocking transactions. They also cover the workload reduction benefits for database administrators. Oracle MyLearn: https://mylearn.oracle.com/ou/course/oracle-database-23ai-new-features-for-administrators/140830/ Oracle University Learning Community: https://education.oracle.com/ou-community LinkedIn: https://www.linkedin.com/showcase/oracle-university/ X: https://twitter.com/Oracle_Edu Special thanks to Arijit Ghosh, David Wright, and the OU Studio Team for helping us create this episode. ------------------------------------------------------- Episode Transcript:

00:00

Welcome to the Oracle University Podcast, the first stop on your cloud journey. During this series of informative podcasts, we’ll bring you foundational training on the most popular Oracle technologies. Let’s get started!

00:26

Lois: Hello and welcome back to the Oracle University Podcast. I’m Lois Houston, Director of Innovation Programs with Oracle University, and with me is Nikita Abraham, Team Lead of Editorial Services.

Nikita: Hi everyone! Last week, we looked at two Oracle Database 23ai new features related to Data Manipulation Language, or DML. One was Unrestricted Parallel DMLs and the other was Unrestricted Direct Loads. Do check out that episode if you missed it.

00:56

Lois: Today, we have Senior Principal Database & MySQL Instructor, Bill Millar, with us. He’s been on several times this season taking us through all the different 23ai new features. In this episode, we’re going to ask him about the Automatic Transaction Rollback feature. Hi Bill! What is automatic transaction rollback and why is it an important feature for database administrators?

01:22

Bill: We can now have transactions that are blocking other transactions, depending on some settings, to automatically roll back. It does require some parameters to be set. Rows basically get locked in a single row. Each row is locked based off of what type of activity is being performed on that row, such as inserts, updates, deletes, merge, select for updates.

01:52

Nikita: And how were things before this feature?

Bill: Traditionally, the database administrator had to research and manually terminate blocking transactions, or there are some things that resource manager might have been able to do.

02:05

Lois: This seems like such a game-changer for DBAs, Bill. So, how does it work?

Bill: So there are some parameters that control the automatic rollback. One is the transaction priority. We're going to set that priority for a transaction either to medium, high, or low. We have the high priority wait target and a medium priority wait target that we can set.

The high wait target will terminate if a medium transaction is blocking that high target based off of the values that we set, the medium transaction can be terminated. A medium transaction will terminate a low priority. So if a transaction designated as low exceeds the blocking time that we set for the medium priority wait time, then it'll be terminated. Whereas, the high priority will terminate both medium and low transactions.

We have the rollback mode. We're either going to roll back or we're going to track, depending on what we're trying to do.

03:10

Nikita: So, if I decide that I want to use automatic transaction rollback... if I decide to implement it...I’ll need to set those parameters, right?

Bill: So we can set those at a session level. We also have some system level wait targets. What are the wait times for the medium, high transactions? How long they are going to wait for those lower transactions?

And then we also have the rollback mode. Are we actually going to roll back or are we just going to track for right now? We have to determine what is going to be the wait times for those transactions that we want to wait before those lower transactions, priority transactions are rolled back?

At that session level, we're going to set...