March 28, 2012 A recent question on the OTN forums asked which PLAN_HASH_VALUE appears in V$SQLAREA when there are multiple child cursors for a single SQL_ID value, when some child cursors have a different execution plan. Certainly, this bit of information must be in the Oracle Database documentation. Let’s check the V$SQLAREA documentation for Oracle Database 11.2: [...]
It’s often useful to keep one’s ear to the ground when one is responsible for database performance and/or efficiency — it’s a talent that I wish more DBAs had: a sense of curiosity about how the database is being used to support particular application use cases.
Today’s post deals with something rather basic, but it speaks to this idea of “agile” collaboration between developers and DBAs around something that has a lot of buzz right now: processing “Big Data” with Hadoop / MapReduce. In particular, a process that someone has already deemed to be “too big” to be accomplished within an existing Oracle database.
Oracle 11.2 introduced a set of new Query Transformations, among others the ability to coalesce subqueries which means that multiple correlated subqueries can be merged into a number of less subqueries.
Timur Akhmadeev already demonstrated the basic principles in a blog entry, but when I was recently involved into supporting a TPC-H benchmark for a particular storage vendor I saw a quite impressive application of this optimization that I would like to share here.
I’ve been working on a lot of good schtuff lately on the area of capacity planning. And I’ve greatly improved my time to generate workload characterization visualization and analysis using my AWR scripts which I enhanced to fit on the analytics tool that I’ve been using.. and that is Tableau.
So I’ve got a couple of performance and capacity planning use case scenarios which I will blog in parts in the next few days or weeks. But before that I need to familiarize you on how I mine this valuable AWR performance data.
Let’s get started with the AWR top events, the same top events that you see in your AWR reports but presented in a time series manner across SNAP_IDs…
March 15, 2012 (Modified March 16, 2012) Several people expressed an interest in using the Beta version of my Hyper-Extended Oracle Performance Monitor 6.0 that has been under development for about a decade. Rather than trying to find a way to deliver the Beta version of the program to those people who left comments in [...]
March 12, 2012 As long time readers of this blog might know, in my free time during roughly the last 10 years I have been working on a program named “Hyper-Extended Oracle Performance Monitor”. Since 2005 or 2006 I have permitted a few people to try the beta versions of the program, thinking that I might [...]
A recent posting on the comp.databases.oracle.server newsgroup pointed me to a rather elderly Ask Tom question (originally posed in July 2004, last updated June 2011) where Tom produced an extraordinary observation. The response times for the following two queries are completely different (on Oracle 9.2 on his data set):
If you are using Oracle Database Appliance (ODA) then this patch is very important to apply. The patch bundle 184.108.40.206.0 has been published just this week and the most important fix from my perspective is the new BIOS version 12010304. Intel CPUs have a feature called Software Controlled Clock Modulation that allows programmatically control of [...]
This is a quick announcement that Method-R is organizing the online class reunion for the participants of their Mastering Oracle Trace Data classes. Cary Millsap and Ron Crisco will entertain us with stories and useful tips around processing and analyzing Oracle 10046 traces. Having Method-R done special training for Pythian about a year ago, I [...]
This is a temporary note to point you to a request from James Morle for a bit of community effort. As spinning rust is gradually replaced by semi-conductor devices, transport latency becomes more significant, so James is trying to get a handle on this aspect of I/O. If you want to help build a coherent picture, read this article and see what you can do about running the test.