Author: user

Well, I have always been and probably always will be poor at coming up with snappy, punning titles for blog posts, so it’s the best I can do. I bought Troubleshooting Oracle Performance by Christian Antognini a while ago (when it was first published, I think) but, as seems to be my way these days,… Continue reading A TOP Book

I’d already made a note to read and blog about Greg Rahn’s Parallel Execution over RAC blog post which is excellent, as usual, but Jonathan Lewis beat me to it 😉 What struck me when I eventually took the time to read it, though, was the link in his post to an Oracle White Paper… Continue reading The Best Oracle Parallel Execution Paper

Some features in this post require a Diagnostics Pack license. I noticed a post on H.Tonguç Yılmaz’s blog about filtering ASH data to look at the actions of a specific instrumented query. There are a few strange things that I was going to comment on but the blog requires me to use a WordPress account… Continue reading Session Level ASH Reports

Features in this post require both Diagnostics and Tuning Pack licenses. If you haven’t seen 11g’s Real Time SQL Monitoring feature, you need to. It’s one of the most useful Oracle performance troubleshooting tools I’ve seen since I started working with Oracle too long ago. I was first aware of it via Greg Rahn’s blog… Continue reading Real-Time SQL Monitoring in SQL Developer

Some features in this post require a Diagnostics Pack license. I’ll get back to adaptive thresholds at some point but something’s been bugging me. I’m not just trying to be controversial but I’ve a feeling I’m about to be, given that ADDM is the probably the most infamous of the 10g ‘Automatic Tuning’ features. What… Continue reading I Love ADDM

Some features in this post require a Diagnostics Pack license. One of my favourite aspects of blogging is that if I were to write a proper article or conference paper, I’d be likely to fix any problems with it as I go (well, the ones I notice!). With blogging, it’s more likely that I’ll just… Continue reading Adaptive Thresholds in 10g – Part 3 (Setting Thresholds)

Some features in this post require a Diagnostics Pack license. Metric Baselines were designed to be easy to implement. There are only two options :- 1) Pick how much recent activity you want to use and let Oracle recompute the statistics based on the most recent metric values over time. (Moving Window) 2) Pick a fixed… Continue reading Adaptive Thresholds in 10g – Part 2 (Time Grouping)

Some features in this post require a Diagnostics Pack license. [I really didn’t want to get into another multi-part blog post, but this has grown longer than I hoped, so I’ll split it up …] One of the more interesting components of the 10gR2 instrumentation improvements is the use of Metric Baselines and Adaptive Thresholds… Continue reading Adaptive Thresholds in 10g – Part 1 (Metric Baselines)

Except it’s not the end, of course. What I mean is that I usually agree with what Miladin Modrakovic said in one of his comments on his first deadlock blog post. “There is always way around.“ As I keep saying, there are many different ways of diagnosing locking problems. Which one works best depends on the situation you’re faced with… Continue reading Diagnosing Locking Problems using ASH/LogMiner – The End

This time, instead of dumping the contents of the log file for a specific Data Block Address (DBA), as in the last part, I’m going to dump it for a specific operation type – Lock Rows (SELECT FOR UPDATE in this case) – which is part of the Row Operations layer (11) and is the… Continue reading Diagnosing Locking Problems using ASH/LogMiner – Part 9