Concurrency … the path to success and the path the failure

Learning is not a spectator sport

Let’s face it. Concurrency is a good thing when it comes to database applications. After all, if there is only a single user of your application, then chances are, it is not a successful application Smile. Of course there are exceptions to this rule, but by and large, most of the applications we build are going to be used by large populations of users. And given the recent publicity of users data and privacy, we can also be pretty confident that we want the data in our applications to be correct at all times.

As a developer, it is absolutely critical to keep concurrency in mind when building applications. Here is a simple demonstration to thrust home the point.

The task assigned to the developer here is simple – transfer move all of the rows satisfying a particular condition from table T1 to table T2. Let’s create our database objects…

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Cool stuff with partition elimination

Learning is not a spectator sport

Sometimes in the IT world, the term “surprise” is not a good one.

“I woke up this morning and got a …my database was down.”

“I ran a SELECT COUNT(*) on my most important table, and got a result of zero rows.”

and so forth. Generally as IT professionals, encountering the unexpected is not a good start to the day Smile.

But sometimes, surprises can be a nice thing.  Here is my example for today – when I found that the database can do a remarkably good job when it comes to reducing the workload with partitioned tables.  

Most people will already be familiar with the concept of partition elimination.  If you have a table partitioned into (say) yearly segments, and you ask for all of the data for the past 2 years, then the optimizer is intelligent enough to only scan the relevant partitions rather than the entire…

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Apex 5 Universal Theme – Navigation Experiment #4

His blog is a gem :)

svenweller

Coloring side menu entries

Sometimes you want to add a little more color to the navigation menu. The idea in one project was to use colors for certain areas in an application. The color would show the user where he is currently working. Whether such colors are a feature that end users like, is still part of an ongoing discussion. But here are the technical details how to implement it.

The example uses a very small apex application that I’ll be using for a DOAG2015 presentation “Exotic SQL” (http://syntegris-doag.de/#vortraege).

Before / After
apex5_sidebar_colored_beforeapex5_sidebar_colored_after

Steps to create this

I explain the changes in detail a little further down.

  1. Create a new List template based upon the current one.
  2. Switch the user interface from the old to the new template
  3. Edit the template
  4. Add colors to the parent list entries
  5. Update alls sub menus to match the parent color

Special Features:

  • can be…

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