Tag: sql

Add ORDER BY to make ANY query faster

Yes it’s SCBT day here in Perth! SCBT = Silly Click Bait Title This post is just a cautionary tale that it is easy to get caught up judging SQL performance solely on a few metrics rather than taking a more common sense approach…

Take care with regular expressions

In an Office Hours session a couple of months back, I covered an important change that comes to regular expressions once you upgrade to 12c Release 2. You can see the video covering the issue here: but for the TL;DR brigade reading this post:…

Gooey GUIDs

Do a quick Google search and you’ll find plenty of blog posts about why GUIDs are superior to integers for a unique identifier, and of course, an equal number of posts about why integers are superior to GUIDs. In the Oracle world, most people…

From file names to directory hierarchy

I had a fun request come in from a colleague the other day.  They had a simple list of fully qualified file names and they needed to present that data in the familiar hierarchical tree layout.  To demonstrate, I took a little trip down…

Concurrency … the path to success and the path the failure

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 .  Of course there are exceptions to this rule,…

Choose your names wisely

It all seems simple enough.  You pick a name for an object…and that is the only object that have than name right ?  For example: SQL> create table MY_UNIQUE_NAME ( x int ); Table created. SQL> SQL> create synonym MY_UNIQUE_NAME for MY_UNIQUE_NAME; create synonym…

NVL vs COALESCE

Jonathan Lewis just published a blog post about NVL and COALESCE and the optimizer costings for each. There is also perhaps a significant difference between NVL and COALESCE in that the former seems to have an in-built optimization for handling bind variables and nulls. …