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Exadata storage indexes

We had a question on AskTOM inquiring about how to handle the issue of only 8 storage indexes being possible on an Exadata engineered system. If you are unfamiliar with what a storage index is, they are part of the suite of features often referred to as the “secret sauce” that can improve query performance on Exadata systems by holding more metadata about the data that is stored on disk. You can get an introduction to the concept of storage indexes here.

Video : Oracle REST Data Services (ORDS) : OAuth Authorization Code

In today’s video we look at the OAuth Authorization Code flow for Oracle REST Data Services.

This goes together with a previous video about first-party authentication here.

Both videos are based on parts of this article.

There are loads of other ORDS articles here.

Delphix XPP explained

This article was originally posted on the Delphix Support blog on 15-Nov 2015, but with the deprecation of the XPP feature with the new 6.0 release and higher, it was decided best to remove this article.

So, I have saved it and posted it here instead, almost 4 years to the day after it was originally posted…

The topic of converting Oracle databases from one of the proprietary
UNIX platforms (i.e. Solaris, AIX, or HP-UX) to Linux seems at first pretty
esoteric and far-fetched.

Meh. Right?

Plus, a lot of folks who have used Solaris, AIX, and HP-UX over the years can
argue that those operating systems have far more capabilities and
technical advantages than Linux, and they may be absolutely correct.  Who wants to get caught up in a religious debate?

Do you work in I.T?

If you do, then you know that only 20% of your I.T work is spent at the office. And no, I’m not talking about telecommuting or working remotely here. I’m talking about the 80% of our time we spend handling all those I.T calls from friends and family Smile

So I was motivated to put together this little ode – dedicated to all of us that have to go the extra mile to keep our loved one’s I.T devices working as they should.

Enjoy and share with all those I.T people in your life Smile

Cloning a schema with one line

In the world of DevOps, continuous integration and repeatable test cases, the demand for being able to

  • quickly build a suite of database objects,
  • utilise it for a series of tests,
  • then throw the objects away

has become far more common. This is one of the many great use cases for pluggable databases with all of the powerful cloning facilities available. In particular, now that you can take advantage of pluggable databases without* incurring additional license fees, there are some great opportunities there…but that is the topic for another post.

DML error logging redux

I posted a nice little feature of DML error logging recently, and a comment came in mentioned that caution is needed with DML error logging because the errors are logged persistently. Hence if you ran a load multiple times, or multiple sessions were utilizing the facility, then the error logging table can quickly become a soup of data that cannot be tracked back to the code your own session was running.

By default this is true, which we can see with a trivial demo. I’ll do the same load of bad rows twice and “forget” to clear out my error table. Here’s my setup – we have a target table called TGT which has rules on nulls and integers being positive, and a source table SRC which has some data that will violate those rules when it comes to loading the data.

The holistic SQL tuning series

I did a set of articles for Oracle Magazine on a more holistic view of SQL tuning. What do I mean by “holistic”? It was a reflection of a common problem that I see when questions come into AskTOM, or when people in the community approach me at conferences, namely, there is an inclination to dive straight into the deepest levels of the tuning exercise:

  • “What index should I create?”
  • “Should I increase the parallel degree?”

etc etc. And as technical practitioners, it is an easy trap to fall into. We too often fail to step back and approach the problem from its true requirement – that of, satisfying a business need. We might end up deep in the code, but we should probably not start there.

Cursor_sharing

Here’s a funny little detail that I don’t think I’ve noticed before – needing only a simple demo script:

The definition of proof

One of the pieces of advice that I often see on the ‘net is that undo space is somehow this incredibly precious thing, and as a consequence, one should always keep the amount of uncommitted changes in the database to a small size.

Personally I think that is baloney (Ed-in reality, as an Australian I have a slightly more powerful choice of term, but lets keep things PG-rated </p />
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A refreshing look at PIVOT

We had an AskTOM question come in recently where our customer was very excited about the PIVOT operator in SQL which lets you transpose rows to columns. This is a very common requirement in applications that want to take data that has been modelled in “pure” relational form, and present in a more “human-digestible” form. There are plenty of posts and examples out there about PIVOT, but if you haven’t seen one, here’s a trivial example just so that you are up to speed for the rest of this post.