SQL*Plus Terminator Torture

“Leave that jar of Nutella alone, it’s got my name on it !”
The context in which Deb issued this injunction to me probably requires some explanation.
It was Friday evening.
Wales had just…well…come second in the latest installment of their eternal battle with the English through the medium of Rugby.
There was no alcohol left in the house.
And only one source of chocolate.
From the safety of the Cupboard under the stairs, to which I had retreated at kick-off – the Welsh do take their Rugby quite seriously – I wondered about my better half’s change of name.
Shorn of it’s chocolate hazelnut spread connotations, you might think that Nutella was quite an nice name for a girl.
It certainly seems appropriate if the “Girl” in question is slightly unhinged by a combination of wine and wounded national pride.

I was going to write something here about how Rugby players all look like the Terminator and use this as a way of introducting the topic at hand. However, I realise that this would simply be too contrived…even for me.
Instead, I’ll jump straight in…

CREATE USER and ALTER USER – changing passwords and a New Year’s Resolution

Monday morning. The first day back at work in the New Year.
Still groggy, having been awoken from my slumber at the insistence of my Darth Vader Lego Alarm Clock, I stagger downstairs in search of coffee.
The clock was a Christmas present from Deb. Whilst clinking around the kitchen, I wonder whether it was intended as a subtle reminder of how she likes her coffee with only a little milk. Yes, she prefers it on the Dark Side.
Then I remember. I usually avoid New Year’s resolutions. I find them to be not unlike a cheap plastic toy at Christmas – there in the morning and then broken by the first afternoon.
This year however, is an exception.

In a recent post about APEX Authentication Schemes, I went to great lengths to ensure that a dynamic SQL statement to re-set a users password was safe from the possibility of injection.
Fortunately, Jeff Kemp took the time to point out a couple of issues with my approach.
As a result, this year, my resolution is to :
READ THE MANUAL.

What follows is the result of keeping this resolution ( so far, at least)…

Implementing a Database Authentication Scheme in APEX

The following tangential opening was written especially for Scott Wesley in the hope that he’ll be minded to point out any errors in what follows. The same applies to Jeff Kemp ( although I don’t know if he’s into the AFL).
Unlike me, both of these guys are APEX experts.

Football. It’s a term that means different things to different people.
To a European, it’s most likely to be a reference to good old Association Football ( or Soccer).
To an American, it’s more likely to be the Grid-iron game.
A New Zealander will probably immediately think of Rugby Union.
An Australian ? Well, it’s probably a fair bet that they’ll think of Aussie Rules Football.

On the face of it, the rules appear rather arcane to an outsider. 18-a-side teams kicking, catching and punching something that resembles a Rugby ball around a pitch that resembles a cricket oval. Then there is the scoring system.
“Nice Behind”, to an AFL player is more likely to be taken as a compliment of their skill at the game than an appreciation of their anatomy.

Then again, it’s easy to scoff at any sport with which you are unfamiliar.
For example, Rugby could be characterised as 30 people chasing after an egg. Occasionally, they all stop and half of them go into some strange kind of group hug. I wonder if the backs ever get paranoid because they think the forwards are talking about them ?

As for soccer, even afficionados will acknowledge that there’s something a bit odd about a game where 22 millionares spend lots of time chasing after one ball…when they’re not rolling around in apparent agony after appearing to trip over an earth worm. I mean, the ball isn’t that expensive, surely they can afford one each ?

The point of all of this ? Well, what is considered to be obscure, eccentric, or just plain odd often depends on the perspective of the observer.

Take APEX authentication schemes for example.
Whilst not the default, Database Authentication is a scheme that is readily available. However, there doesn’t seem to be much written on this subject.

In contrast, there is a fair bit out there about APEX Custom Authentication. A lot of it would appear to re-enforce the idea that implementing security by hand is fraught with difficulty.
Just one example can be seen here.

If we were to approach this topic from the perspective of looking to migrate an elderly Oracle Forms application – where each user has their own database account – to APEX, we might be attracted to the idea of a Database Authentication Scheme and want to find out more.

What follows is my adventure through setting up such an Authentication Scheme.
Specifically, I’m going to cover :

• Creating an APEX Database Authentication Scheme
• Default behaviour
• Adding a Verification Function to restrict access to a sub-set of Database Users
• The vexed question of password resets

APEX 503 – Service Unavailable – And you don’t know the APEX_PUBLIC_USER Password

It’s probably Monday morning. The caffeine from your first cup of coffee has not quite worked it’s way into your system.
The cold sweat running down the back of your neck provides an unpleasant contrast to the warm blast of panicked users as they call up to inform you that the Application is down.
APEX, which has been behaving impeccibly all this time, has suddenly decided to respond to all requests with :

503 – Service Unavailable.

The database is up. The APEX Listener is up. But something else is up. APEX just doesn’t want to play.
Better still, the person who set up the APEX in the first place has long-departed the company. You have no idea how the Apex Listener was configured.

Out of sympathy with your current predicament, what follows is :

• How to confirm that this problem is related to the APEX_PUBLIC_USER (the most likely cause)
• A quick and fairly dirty way of getting things back up and running again
• How to stop this happening again

Note: These steps were tested Oracle Developer Day VM with a 12c database running on Oracle Linux 6.5. In this environment, APEX is configured to run with the APEX Listener.

Kilobytes, Kibibytes and DBMS_XPLAN undocumented functions

How many bytes in a Kilobyte ? The answer to this question is pretty obvious…and, apparently, wrong.
Yep, apparently we’ve had it wrong all these years for there are, officially, 1000 bytes in a Kilobyte, not 1024.
Never mind that 1000 is not a factor of 2 and that, unless some earth-shattering breakthrough has happened whilst I wasn’t paying attention, binary is still the fundemental basis of computing.
According to the IEEE, there are 1000 bytes in a kilobyte and we should all get used to talking about a collection of 1024 bytes as a Kibibyte

Can you imagine dropping that into a conversation ? People might look at you in a strange way the first time “Kibibyte” passes your lips. If you then move on and start talking about Yobibytes, they may well conclude that you’re just being silly.

Let’s face it, if you’re going to be like that about things then C++ is actually and object orientated language and the proof is not in the pudding – the proof of the pudding is in the eating.

All of which petulant pedantry brings me on to the point of this particular post – some rather helpful formatting functions that are hidden in, of all places, the DBMS_XPLAN pacakge…

APEX and Privileges Granted through Roles

The mystery has finally been solved. England’s surrendering of the Ashes last winter was nothing to do with Australia being a much better cricket team. Thanks to Kevin Pietersen’s recently published Autobiography, we now know that the problem was that there were rather too many silly points in the England dressing room.
Moving swiftly on from that weak pun, the subject at hand can also be rather mystifying at first glance.

In a “traditional” Oracle Forms application, you would have one database user per application users.
Connections via the Application to the database would be done as the individual users.
It’s quite likely that database roles would be used to grant the appropriate privileges.

For applications using other web technologies, the application may interact with the database via a single account, often that of the Application Owner. Whether or not this is a good idea is probably a discussion for another time.

For now though, the question we’re asking is, how an APEX application connect to the database ?
On the face of it, it would seem that it’s pretty similar to the second of the two approaches above. APEX connects as the Parsing Schema (usually the application owner).
As Kevin will tell you, appearances can be deceiving…

Going dotty – Generating a Filename containing a parameter value in SQL*Plus

As I have alluded to previously, I was not born in the UK.
Nope, my parents decided to up-sticks and move from London all the way to the
other side of the world, namely Auckland.
Then they had me. Then they came back.
To this day, they refuse to comment on whether these two events were related.

I went back to New Zealand a few years ago.
As I wandered around places that I hadn’t seen since I was five, it was strange how memories that I had forgotten came flooding back.
That last sentence doesn’t make much sense. It’s probably more accurate to say that memories I hadn’t thought about for years came flooding back.

I recently remembered something else I once knew, and then forgot – namely how to generate a SQL*Plus file name which includes a parameter value.