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Video Tutorial: XPLAN_ASH Active Session History - Part 3

The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality continuing the actual walk-through of the script output.

More parts to follow.

Video Tutorial: XPLAN_ASH Active Session History - Part 2

The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality has been published. In this part I begin the actual walk-through of the script output.

More parts to follow.

Video Tutorial: XPLAN_ASH Active Session History - Introduction

I finally got around preparing another part of the XPLAN_ASH video tutorial.

This part is about the main funcationality of XPLAN_ASH: SQL statement execution analysis using Active Session History and Real-Time SQL Monitoring.

In this video tutorial I'll explain what the output of XPLAN_ASH is supposed to mean when using the Active Session History functionality of the script. Before diving into the details of the script output using sample reports I provide some overview and introduction in this part that hopefully makes it simpler to understand how the output is organized and what it is supposed to mean.

This is the initial, general introduction part. More parts to follow.

Parallel Execution Skew - Summary

I've published the final part of my video tutorial and the final part of my mini series "Parallel Execution Skew" at AllThingsOracle.com concluding what I planned to publish on the topic of Parallel Execution Skew.

Anyone regularly using Parallel Execution and/or relying on Parallel Execution for important, time critical processing should know this stuff. In my experience however almost no-one does, and therefore misses possibly huge opportunities for optimizing Parallel Execution performance.

Since all this was published over a longer period of time this post therefore is a summary with pointers to the material.

If you want to get an idea what the material is about, the following video summarizes the content:

Analysing Parallel Execution Skew - Without Diagnostics / Tuning Pack License

This is the third part of the video tutorial "Analysing Parallel Execution Skew". In this part I show how to analyse a parallel SQL execution regarding Parallel Execution Skew.

If you don't have a Diagnostics / Tuning Pack license the options you have for doing that are quite limited, and the approach, as demonstrated in the tutorial, has several limitations and shortcomings.

Here is the video:

Analysing Parallel Execution Skew - Data Flow Operations (DFOs) And DFO Trees

This is the second part of the video tutorial "Analysing Parallel Execution Skew". In this part I introduce the concept of "Data Flow Operations (DFOs)" and "DFO Trees", which is what a Parallel Execution plan is made of. DFOs / DFO Trees are specific to Parallel Execution and don't have any counterpart in a serial execution plan.

Understanding the implications of DFOs / DFO Trees is important as prerequisite for understanding some of the effects shown in the later parts of the video tutorial, hence I covered this as a separate topic.

Note that this tutorial also demonstrates some new 12c features regarding Parallel Execution, in particular how Oracle 12c now lifts many of the previous limitations that lead to the generation of multiple DFO Trees.

Here is the video:

Analysing Parallel Execution Skew - Video Tutorial

Along the new mini series "Parallel Execution Skew" at "AllThingsOracle.com" that provides some information what you can do if you happen to have a parallel SQL execution that is affected by work distribution problems I'm publishing a series of video tutorials that explain how you can actually detect and measure whether a SQL execution is affected by skew or not.

Originally this tutorial was planned as one part (Part 5 actually) of the XPLAN_ASH video tutorial series, however so far I've only managed to publish just the inital two parts of that series, and these are already a bit outdated as I've released new versions of the XPLAN_ASH tool with significant changes and enhancements since then.

New Version Of XPLAN_ASH Utility

A new version of the XPLAN_ASH tool (detailed analysis of a single SQL statement execution) is available for download. The previous post includes links to video tutorials explaining what the tool is about.

As usual the latest version can be downloaded here.

The new version comes with numerous improvements and new features. The most important ones are:

  • Real-Time SQL Monitoring info included
  • Complete coverage including recursive SQL
  • Improved performance
  • 12c compatible
  • Simplified usage

New Version Of XPLAN_ASH Tool - Video Tutorial

A new major release (version 3.0) of my XPLAN_ASH tool is available for download.

You can download the latest version here.

In addition to many changes to the way the information is presented and many other smaller changes to functionality there is one major new feature: XPLAN_ASH now also supports S-ASH, the free ASH implementation.

If you run XPLAN_ASH in a S-ASH repository owner schema, it will automatically detect that and adjust accordingly.

XPLAN_ASH was tested against the latest stable version of S-ASH (2.3). There are some minor changes required to that S-ASH release in order to function properly with XPLAN_ASH. Most of them will be included in the next S-ASH release as they really are only minor and don't influence the general S-ASH functionality at all.