Explaining the Explain Plan – How to Read and Interpret Execution Plans

 

Examining the different aspects of an execution plan, from cardinality estimates to parallel execution, and understanding what information you should glean from it can be overwhelming even for the most experienced DBA.

That’s why I’ve put together a series of short videos that will walk you through each aspect of the plan and explain what information you can find there and what to do if the plan isn’t what you were expecting.

What is an Execution Plan?

The series starts at the very beginning with a comprehensive overview of what an execution plan is and what information is displayed in each section. After all, you can’t learn to interpret what is happening in a plan, until you know what a plan actually is.

How to Generate an Execution Plan?

Although multiple different tools will display an Oracle Execution Plan for you, there really are only two ways to generate the plan. You can use the Explain Plan command, or you can view the execution plan of a SQL statement currently in the Cursor Cache using the dictionary view V$SQL_Plan. This session covers both techniques for you and provides insights into what additional information you can get the Optimizer to share with you when you generate a plan. It also explains why you don’t always get the same plan with each approach, as I discussed in an earlier post.

How to use DBMS_XPLAN to FORMAT an Execution Plan

The FORMAT parameter within the DBMS_XPLAN.DISPLAY_CURSOR function is the best tool to show you detailed information about a what’s happened in an execution plan including the bind variable values used, the actual number of rows returned by each step, and how much time was spent on each step.  I’ve also covered a lot of the content in this video in a previous post.

Part 2 of the series will cover Cardinality Estimates and what you can do to improve them!

Remember you can always get more information on the Oracle Optimizer on the Optimizer team’s blog.

Data-Driven Apps – What are they and the easiest way to develop them

At the moment, we hear a lot about how businesses need to become data-driven to remain competitive, how business need to understand their customer’s needs and quickly deliver value to those customers.

But how do you do that?

You take advantage of data-driven apps that allow users to create value or insights from data in real-time. 

What are Data-Driven Apps?

Data-driven apps operate on a diverse set of data (spatial, documents, sensor, transactional, etc.) pulled from multiple different sources, often in real-time and create value from that data in very different ways to traditional applications. For example, they may use Machine Learning to make real-time recommendations to customers or detect fraudulent transactions. Or use Graph analytics to identify influencers in a community and target them with specific promotions or perhaps use spatial data to keep track of deliveries.

These apps are also frequently deployed on multiple platforms, including mobile devices as well as standard web browsers, which means they need a flexible, scalable and reliability deployment platform. Given the demands on these apps, they need to be continuously developed to adapt to new use cases or user needs, and all updates must happen online as they have to be available 24×7.

When building data-driven apps, developers need to leverage an ever-increasing set of data processing and machine learning algorithms to meet these requirements.

So how should you go about developing and deploying data-driven apps quickly, efficiently, and more importantly, in a maintainable way?

Data-Driven Techniques and Technology

You take a data-first approach, or as A. Neil Pappalardo put it ‘A Minimize Code, Maximize Data‘ approach. In other words, you bring the algorithms to the data, not the data to the algorithms.

In the video below, I explain how to take advantage of the built-in features and functionality of the Oracle Database to develop and deploy data-driven apps efficiently. I also share some easy to follow code examples to demonstrate how much simpler your application code can be if you use this approach! Continue reading “Data-Driven Apps – What are they and the easiest way to develop them”

A Special Episode of Real Time BI

Yesterday I had the privilege to join Stewart Bryson, Danny Bryant and Bobby Curtis for a special episode of Real Time BI. During the show we had an opportunity to chat about some of our favorite new features in Oracle Database 12c, the transition to the cloud and what you can expect at the upcoming GAOUG Tech Days.

All four of us will be speaking at the Tech Days in May and from what I hear it’s going to be a great couple of days in Atlanta. So if you are in the area, it would be great to have you join us.

You can check out the full episode below!

12.2 and Tim Tams

Yesterday saw Oracle complete the release of Oracle database 12c Release 2 when the software became available for download on Oracle.com for both Linux & SPARC.

Earlier this year I was lucky enough to have an opportunity to grab a coffee and enjoy some Tim Tams (cookies) with Connor McDonald, my fellow askTOM team member, and chat about our favorite new features in 12.2. I thought you might enjoy see what we had to say about the new features and the enhancements that could make your life a lot easier.

Happy viewing!