Ponedeljek 13. oktober 2014

- Udeležba na delavnici je mogoča v sklopu udeležbe na strokovnem srečanju SIOUG 2014.
Zaradi omejenega števila mest v dvorani je potrebna dodatna prijava v prijavnici SIOUG 2014.


Troubleshooting with ASH and Understanding Table Compression


This seminar is comprised of two popular seminars presented recently at Oracle users group conferences in the USA, Asia, and Europe.  Both seminars demonstrate the mindset of testing and empirical proof, and both arose out of real-life challenges.

The first seminar, entitled "RDBMS Forensics:  Troubleshooting with ASH", uses two different real-life case studies to illustrate how to use Active Session History (ASH) within Oracle database to investigate, gather facts, and resolve a specific error condition:  the ORA-03135 / ORA-03136 error indicating "inbound connection timeout".  There is a lot of speculative discussion on the internet and on MyOracleSupport, but nothing useful that relates to what might be causing the error, nor what might be done to resolve it.  The information that is available is based on guessing and invalid inferences, making it worse than useless;  harmful in fact.

Resolving such problems is not art, it is process, and the intent of this presentation is to use these two case studies to demonstrate that process, and also to show how database components such as AWR and ASH, typically thought of as "performance tuning" tools, are also useful diagnostic tools. Attendees to this presentation will learn a forensic, empirical approach to trouble-shooting and also see a demonstration of a complex problem resolution  task resulting in a non-intuitive but empirically sound conclusion.

The second seminar is entitled "Three Types Of Table Compression", which refers to the fact that Oracle only documents two types of table compression:  BASIC/OLTP and HCC.  This presentation describes a third type of table compression that has existed in the Oracle product for decades, and the purpose of the presentation is to illustrate the various situation where each of the three types of compression, the two documented methods plus the ancient trailing NULL columns method, might each work best.  In order to understand how each of the methods of compression work and when they work best, the presentation walks through a detailed analysis of the inner workings of each mechanism.

These presentations will teach attendees many things, such as:
1.    What is Active Session History (ASH) and how is it part of the Automatic Workload Repository (AWR)?
2.    What information can be found within ASH, and how is it similar to SQL tracing, except stored within the database?
3.    How can ASH be used to troubleshoot faults and failures which have occurred in the past?
4.    How Oracle stores data in rows and blocks
5.    How Oracle compresses table data and how each method of compression works over the lifecycle of the data

The most important thing that this seminar will teach is how rich Oracle is with data for investigators, and how little is hidden to those patient enough to use the right tools to extract it.


Tim Gorman Workshop