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Security is in the news again.  It seems there’s no greater click-bait than a story about indecent photos of beautiful young Hollywood actresses stolen from their iPhones. Find a way to rope a cute kitten into the story and the Internet might very well explode. The current theories abounding seem to suggest that the vulnerabilities lay not with Apple, but… Continue Reading →

All Things Oracle Full Articles, Database Administration

In part 9 we saw an example of a simple nested loop join where the basic method for interpreting the numbers in an execution plan started to break down because the arithmetic used by the optimizer to calculate the resource costs for the plan wasn’t consistent with the visual representation of the mechanics of the run-time path. In this instalment we’re… Continue Reading →

All Things Oracle Full Articles, Database Administration, Database Development

In part 8 we looked at a very simple execution plan involving a hash join; but that example was too simple to give us the full flavour of the arithmetic involved in Oracle’s predictions because every operation executed just once. We need to see some plans where each execution of a parent operation could requires multiple executions of its child… Continue Reading →

All Things Oracle Full Articles, Database Administration, Database Development

What is cloning? Cloning is a process of copying an existing installation to a different server or location. Cloning is similar to an Oracle installation except Oracle universal installation performs the actions in a special mode called “clone mode”. Starting from 10g onwards, Oracle supports cloning and users can easily clone existing Oracle installations. The source and destination servers should… Continue Reading →

10g, 11g, All Things Oracle Full Articles, Database Administration, Database Development

It’s time to move away from the shape of an execution plan and turn our attention to some of the numerical information we get from the plan. In this article we’re going to look only at the predictions that the optimizer makes (explain plan), postponing any investigation of actual run-time figures (v$sql_plan_statistics_all) for future instalments. Getting Started As a reference… Continue Reading →

All Things Oracle Full Articles, Database Administration, Oracle Database

In Part 1, I described how data security is critical to the modern enterprise business world and the key role it plays, as well as some of Oracle 12c’s security features.  In Part 2, I am going to touch how to apply security controls in network, storage and backup levels. Also, a few selective Oracle database 12c new security features… Continue Reading →

12c, All Things Oracle Full Articles, Database Administration, Oracle Database

In the final part of this series I want to cover one last source of Parallel Execution Skew: Skew caused by Outer Joins. If you have Outer Joins where the majority of foreign key values is NULL, this can lead to the following symptoms: From a processing point of view for a parallel outer join, the NULL value in the foreign… Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles, Database Administration, Database Development, Oracle Database, Performance Tuning, Troubleshooting

When we examine an execution plan, we’re usually trying to work out the mechanical steps that Oracle took to produce a result set. When we do this, it’s important to remember that the text that Oracle optimized wasn’t necessarily the same as the statement we originally wrote. Oracle may have transformed our statement before passing it through the optimization engine…. Continue Reading →

All Things Oracle Full Articles, Database Administration, PL/SQL

Oracle Database 12c is designed for the cloud and introduces Multitenant Architecture with more than 500 new features. It enables customers to make more efficient use of their resources and reduce IT costs. What is Multitenant Architecture? Oracle 12c now introduces multitenant architecture featuring pluggable databases, which makes it easy to consolidate your databases on to the cloud, deliver high… Continue Reading →

12c, All Things Oracle Full Articles, Database Administration, Oracle Database

In part 5 of this series we examined a couple of examples where you had to handle the “first child first” rule with a little care. In part 6 we continue this exploration to look at a general principle – the “pushed subquery” – where the “first child first” could lead you to the wrong conclusion. Access or Filter If… Continue Reading →

All Things Oracle Full Articles, Database Administration, Database Development