One of the easiest ways to understand something is to see a visualization. Looking at Active Session History (ASH) data is no exception and I’ll dive into how to do so with R and how I used R plots to visually present a problem and confirm a hypothesis. But first some background…
Frequently DBAs use the Automatic Workload Repository (AWR) as an entry point for troubleshooting performance problems and in this case the adventure started the same way. In the AWR report Top 5 Timed Foreground Events, the log file sync event was showing up as the #3 event. This needed deeper investigation as often times the cause for longer log file sync times is related to longer log file parallel write times.
I’ve seen some posts on the blogosphere where people attempt to explain (or should I say guess) how Exadata Smart Flash Logging works and most of them are wrong. Hopefully this post will help clear up some the misconceptions out there.
The following is an excerpt from the paper entitled “Exadata Smart Flash Cache Features and the Oracle Exadata Database Machine” that goes into technical detail on the Exadata Smart Flash Logging feature.
Today I want to show what kind of IO performance we can get from Oracle Database Appliance (ODA). In this part, I will focus on hard disks. That’s right — those good old brown spinning disks. I often use Oracle ORION tool to stress-test an IO subsystem and find it’s limits. It’s a very simple [...]
In addition, here are some OLTP demos that demonstrate how much performance and throughput can be wasted by poor design and suboptimal database programming.
OLTP Performance – The Trouble with Parsing
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OLTP Performance – Concurrent Mid-Tier Connections
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