Oracle Scene Winter 2016, issue 62, by Franck Pachot. The Oracle Database Appliance is not new. The idea comes from early 2002 with the ‘Row Iron’ plan: an appliance with Sun server and Oracle Database. The idea was resurrected in 2011 with ODA V1 and has evolved through capacity and flexibility to X3-2, X4-2 and X5-2. This year the new one, X6-2 has been announced with some major changes. Read more
All posts by Franck Pachot
1st edition 2016 of the RedStack magazine (formerly called “DOAG/SOUG-News”). Article written by Franck Pachot, about the subject: “What gain would you make with a transition to Exadata? – Part II ” (article in French)
If you wish to read the part l (article in French), please click here.
If you wish to read the part lI (article in French), please click here.
Spring 2015, Franck Pachot. You must have system statistics if you want the optimizer to evaluate correctly the cost of full table scans vs. index access. But you have two options to gather them: NOWORKLOAD and WORKLOAD. The latter seems to be the more accurate one because it fits your workload. But do you really know how they are calculated?
Automn 2014, Frank Pachot. Usually, the conclusion comes at the end. But here I will clearly show my goal: I wish I will never see the optimizer index cost adj parameters again. Especially when going to 12c where Adaptive Join can be completely fooled because of it. Choosing between index access and full table scan is a key point when optimising a query and historically the CBO came with several ways to inﬂuence that choice. But on some systems, the workarounds have accumulated one on top of the other – biasing completely the CBO estimations. And we see nested loops on huge number of rows because of those wrong estimations.
Winter 2014, Franck Pachot. 12c came with two new features related to statistics gathering. In the first part I’ll show some important effects to know before using Online Statistics Gathering – which are there by default. And then we will see how it combines with Session Private Statistics when we are on a Global Temporary Table for a transparent improvement of execution plans.