ORA-01775 – Looping Chain of Synonyms and Epic Football Punditry

In 1990, Liverpool became English League Champions for the 10th time in 15 seasons.
Despite this impressive track record, my Dad came over all Yoda-esque and confidently predicted that they would not win The Title again in his lifetime.
Since then, Liverpool have won everything else, including the Champions League – OK Dad , the European Cup – but the prediction has held.
In fact, it’s gone on so long that it probably qualifies as a prophecy by now.
Before the start of each season, I can assess Liverpool’s prospects, by simply enquiring after his health.
“Musn’t grumble, ‘cos if you do no-one bloody listens !” can be taken as a synonym for “I’ll be around for a while yet, so don’t waste your money on backing Liverpool to win it this season”.
Which brings us to the subject of this post – namely the apparently random nature of the ORA-01775 error, where synonyms are concerned…

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Easy Listening with Datapump in the SQLDeveloper DBA Module

There are a number of ways to transfer data between Oracle Databases, one of which is to use the PL/SQL Datapump API – DBMS_DATAPUMP.
If you wish to avail yourself of this utility but find the syntax a bit fiddly, you always have the option of getting SQLDeveloper to do (most of) it for you.
What we’re talking about here is how to persuade the SQLDeveloper DB module to :

• Create and execute a custom Datapump export job
• do most of the work creating an import of a subset of the exported data

…

Adding an item to the Ubuntu Unity Launcher

I would begin this post by saying something pithy about the latest Brexit crisis gripping the nation. However, watching any news or current affairs program at the moment leaves me feeling rather like this :

Fortunately, I had a new version of SQLDeveloper to install on my Ubuntu 16.04 laptop to take my mind off things.
After installing the software, I forgot – as I almost always do – how to add a new item to the Unity Launcher, so I thought I’d write down the steps this time.

Unity is similar to Gnome, KDE and – as it turns out – XFCE in that it seems to follow the freedesktop.org Desktop Entry Specification.
So, all I need to do is :

• create a .desktop file in a suitable location to tell Unity how to run SQLDeveloper
• add it to the Unity Launcher

Installing APEX and ORDS on Oracle 18cXE on CentOS

It’s been rather a trying week.
Wales beat England in the Rugby on Saturday and every Welsh person alive has been observing the ancient tradition of rubbing English noses in it ever since.
My claim to Welsh heritage by marriage have been given short-shrift by Deb, whose accent has become rather more pronounced ever since the final whistle.

All in all, the onslaught of Welsh chauvinism has left me feeling rather like this :

Until things blow over, I’ve decided to spend more time in the shed. Fortunately, the Wifi signal is still pretty good so I’ve decided to use the free time by installing APEX 18.2 into an Oracle 18c RDBMS. As I’ve got time on my hands ( celebrations are unlikely to fizzle out for a couple of months yet), I’ve decided to follow Oracle’s recommendation and configure it to run on ORDS 18.4.
Specifically, what I’ll be covering here is :

• installing APEX 18c
• installing ORDS 18c
• configuring APEX to run on ORDS
• configuring ORDS to run on HTTPS with self-signed SSL certificates
• using systemd to start ORDS automatically on boot

That should keep me occupied for a while…

Oracle Create Schema – multiple DDL statements in a single transaction

I was going to begin with some extended Brexit metaphor to illustrate the chaos and confusion that can ensue when you first encounter Oracle’s CREATE SCHEMA command.
Fortunately, the Dutch Government saved me the trouble :

Much as I’d like to believe that the Cookie Monster has finally overcome his Sesame Street type casting, I can’t help noticing that the Brexit Monster never seems to in the same room as this guy…

In Oracle, the term “schema” is used interchangeably with the term “user”. Creating a user in Oracle automatically creates a schema of the same name belonging to that user.
The process is so seamless that it’s almost impossible to tell where one begins and the other ends.
You may therefore be somewhat confused the first time you encounter Oracle’s CREATE SCHEMA command…

Pi in a time of Brexit – Remote Controlling Raspberry Pi from Ubuntu using VNC

What with Larry the Downing Street Cat and Palmerston, his counterpart at the Foreign Office, Teddy suspects he knows the real reason for the Country’s current travails.
Here he is, doing his best Boris Johnson impression :

“No wonder Brexit’s a Cat-astrophe !”

In an attempt to distract myself from the prospect of the country being ruined by this feline consipracy, I’ve been playing with my new Raspberry Pi Model 3 B-spec.
At some point, I’m going to want to connect remotely to the Desktop on the Pi. What follows is how I can do this using VNC…

Using a Proxy User for Code Deployment in Oracle

“Proxy Users !” exclaimed Debbie.
“I say, that’s rather harsh don’t you think ?” came the rather startled reply from her boss.
Debbie sighed. They were in the midst of a discussion on the subject of how best to deploy database changes to multiple schemas.
“I meant”, she replied with iron patience, “that we could set up a proxy user to connect as each application owner in turn. That way, we wouldn’t have to grant those CREATE ANY privileges that get auditors so worried”.
“Oh, I see”, said Mike, who didn’t.
Not for the first time, Debbie wondered whether she had been lumbered with a less competent man as her boss simply in order to imbue this post with a semblance of social realism.
“I think”, she said, “that it’s time to move on to the techie bit.”
Debbie is right, as usual…

In order to make a change in Oracle ( or any database for that matter), you need at some point to connect to the database and run some SQL.
This is relatively straightforward if you are using the schema that is – or will be – the owner of the objects you are creating or changing.

However, this may not be possible if the account is identified externally or – in more recent releases – it’s a schema only account.
So, what is the best way to setup and use an account to make such changes in other schemas ?