Thursday, July 27, 2006

Training Class (Final Day)

To round off the material covered in this class the following topics were covered today:
  1. Tuning Block Space Usage.
  2. Tuning I/O.
  3. Tuning PGA and Temporary Space.
  4. Performance Tuning: Summary.

I found the Tuning I/O lecture somewhat interesting. The first portion of the lecture focused on the advantages and disadvantages of the various forms of RAID protection. While informative, I could've spent 5 minutes on Google had I not already been armed with the knowledge of this technology. The remainder of this lecture focused on ASM (Automatic Storage Management). This rather non-trivial feature in 10g sounds very cool; define some Data disk group(s) , the relevant protection and striping granularity and let Oracle do the all of the I/O tuning. Of course, this is a severe over simplification of what it really does (or doesn't, as your mileage may vary). But, the point is, this feature is supposed to free the DBA from the often times laborious chore of tuning the I/O subsystem. Truthfully, I think the degree to which Oracle touts the hands-off nature of this feature is overstated; especially for busy production systems. I, nor anyone in the class, had worked with the product. Consequently, I feel there are probably very few shops out there migrating their production databases to ASM. Is it more of a political battle? After all, if DBAs will be able to someday create and manage the logical volumes/file systems this might make the System Administrators feel a little encroached upon. It is just a hunch, but widespread conversions to ASM will probably not happen anytime soon. Anyone reading this blog have any good/bad experience with ASM in a production environment? I am very interested in your feedback.

The most engaging lecture of the day was the Tuning Block Space Usage. I am really keen to the Automatic Segment Space Management (ASSM) feature. This feature warrants serious consideration given the upside: free list elimination and a considerably more robust approach to reusing blocks for inserts. As much as I liked the discussion on ASSM, the subsequent topic grabbed my utmost attention: segment shrinking. What a great (and might I add way overdue) feature. If one of my production environments was on 10g today I could see using this tool to reclaim vast amounts of space in some of my very large heap tables, index-organized tables and indexes. Oracle claims that the majority of the work can be done online. Moreover, the indexes associated with your heap tables are still usable even after the row movement inherent to the SHRINK has completed. I like the idea of having the freedom to perform these "online" activities, but I still prefer to perform these kinds of operations during quite periods. The course material gives a fantastic, albeit brief, description of the mechanics. Very nice Oracle! Once again, are there any readers of this blog that have experience with this feature and want to share your experiences?

The final two lectures, Tuning PGA and Temporary Space and Performance Tuning Summary, were good, but not great. The material seemed to belabor a few points.

In summary, if you are considering taking this course I think you are best served if you do not have much 10g experience in production environments. If your experience with 10g and some of the "tuning" features is even moderate, I recommend you not take the course. Your time would be better spent reading up on this material in the Oracle documentation set.

Eric's rating of the course: B+.


Anonymous Anonymous said...

Thanks Eric for your lengthy review of the class. If I understand what you have written, it sounds like the 10g performance tuning class is moderately better than the 9i version. Always of course subjected to the variable of the experience of the instructor and how well they contribute relevant "not quite in the material" outside perspective.

It is always hard to get enough time to play with a new release when you are busy with real work in a prior one. That sometimes makes a good valid argument for taking classes that might not be an exact match.

Thanks again for the review.

7/29/2006 8:14 PM  
Blogger jason said...

Hi Eric,

We have just migrated our production db from 10.1 solaris & veritas
to 10.2 linux & ASM

performance has been very favourable, equally importantly stability has been excellent. this is RAC implementation and when we first began looking at this the only certified way of storage for a 10.2 linux RAC db was ASM.

my company is at the heart of uk internet, so stability is very very important to us.

8/07/2006 4:23 PM  
Blogger Eric S. Emrick said...

Hi Jason,

Thank you for the feedback. So, in your experience, ASM works as prescribed?


8/09/2006 7:38 AM  
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