Kyle Hailey has started putting together a much needed Oracle wait event reference. You can access it here. By the way, Oracle documentation also has a wait event reference section, it has more events, but it's less detailed... I have plans to go deep into some wait events and cover some less common ones in tech.E2SN too... in the future ;-)

Tanel Poder
Cool stuff, Internals, Oracle, Performance, Tuning

Coskan Gundogar and Karl Arao have written two interesting articles about Oracle performance analysis and visualization, check these out! Coskan's article: http://coskan.wordpress.com/2010/01/27/working-with-statspack-part-1a-diagnosis/ Karl's article: http://karlarao.wordpress.com/2010/01/31/workload-characterization-using-dba_hist-tables-and-ksar/ Note that in March I will be releasing PerfSheet v3.0, which will have lots of improvements! ;-)

Tanel Poder
Cool stuff, Oracle, Performance

In my Beyond Oracle Wait interface article I troubleshooted a test case where an execution plan somehow went "crazy" and started burning CPU, lots of logical IOs and the query never completed. I have uploaded the test case I used to my new website, to a section where I will upload some of my demo scripts which I show at my seminars (and people can download & test these themselves too): http://tech.e2sn.com/oracle-seminar-demo-scripts Basically what I do is this: I run the query with bind variable values where only a handful of rows match the filter condition. Thus Oracle picks nested loop join (and indexed ...

Tanel Poder
Oracle, Performance, SQL, Troubleshooting

I have been very busy over last months (as you see from the lack of blog entries). Part of the reason is that I've been building new seminar material and now I'm pleased to announce some first seminar dates! I have updated new seminar dates and cities in m new webpage: http://tech.e2sn.com/oracle-training-seminars From April 2010 I offer total 3 different seminars Advanced Oracle Troubleshooting v2.0 (3 days) Advanced Oracle SQL Tuning (3 days) Partitioning and Parallel Execution for Performance (1 day) I have rearranged the Advanced Oracle Troubleshooting class based on customer feedback, removed some content, added new content and I think this deserves a new version ...

Tanel Poder
Cool stuff, Oracle, Oracle 11g, Oracle 11gR2, Performance, SQL, Troubleshooting

I just added Tony Hasler's blog to my blogroll. He has lots of useful and very practical stuff in his blog, so I recommend you to check it out. He has a serious amount of even more useful stuff in his head (I've had some very interesting discussions with him) so hopefully additional blog followers motivate him to write all of that stuff out! ;-) http://tonyhasler.wordpress.com/

Tanel Poder
Cool stuff, Oracle

In addition to RSS which I'll be setting up for tech.e2sn.com soon, I will be posting Twitter updates to my account tanelpoder I aim to spend some 30 minutes every day, writing new stuff to tech.e2sn. I will probably not gonna be posting these updates to my blog to reduce this noise... So, if you want to be first to know about article, script, tool updates at tech.e2sn then follow my tweets! http://twitter.com/tanelpoder

Tanel Poder
Cool stuff, Oracle

I have published a new article to tech.e2sn.com about recursive sessions and ORA-00018: maximum number of sessions exceeded error message: http://tech.e2sn.com/oracle/oracle-internals-and-architecture/recursive-sessions-and-ora-00018-maximum-number-of-sessions-exceeded Note that I'm working on setting up RSS feed for tech.e2sn too, coming soon :)

Tanel Poder
Administration, Oracle, Troubleshooting

In early January I wrote that I'm gonna start organizing the more serious and practical Oracle content into my new website and I'll leave my blog for Oracle hacks, my (IT) observations and philosophy, general thoughts and just fun. It's time to publish the newsite now with an application demo rototype which gives some clue of what kind of features will there be in the secret project I've been working on for several months with my friend and business partner. The website is located here: http://tech.e2sn.com E2SN does have a meaning, but I'll leave it a secret for now ( you are free to ...

Tanel Poder
Administration, Cool stuff, Internals, Oracle, Performance, Productivity, SQL, Tools

What you see below is a common problem. Someone sends you (or posts to a forum) a wide execution plan, which is unreadable because of wrapped lines. For example, this one below: -------------------------------------------------------------------------------- ------------------- | Id  | Operation                   | Name                    | E-Rows |  OMem | 1Mem | Used-Mem | -------------------------------------------------------------------------------- ------------------- |   0 | SELECT STATEMENT            |                         |        |       | |          | |   1 |  SORT AGGREGATE             |                         |      1 |       | |          | |*  2 |   HASH JOIN                 |                         |     13 |  1102K| 1102K|  355K (0)| |*  3 |    HASH JOIN                |                         |     13 |   988K| 988K|  367K (0)| |*  4 |     HASH JOIN               |                         |     13 |   921K| ...

Tanel Poder
Administration, Oracle, Productivity, Tools, Unix/Linux

This is the second part of the joint blog "project" with James Morle, called "The Wait Interface Is Useless (Sometimes)". We already did a joint presentation on this topic at UKOUG and more conferences will follow :) Read the first part by James here for intro. So, where do we go when Oracle's wait interface doesn't help us? We will show multiple techniques over time, but here's where I normally continue when wait interface is "useless". I use V$SESSTAT. Oh, were you expecting something more "advanced" instead of boring old V$SESSTAT's performance counters which has been available in Oracle for ages? ;-) Well, there is ...

Tanel Poder
Internals, Oracle, Performance, Troubleshooting