Implementing Arc Relationships with Virtual Columns? Or Not?

I wrote a post some time ago about implementing arc relationships using virtual columns.
Recently, Toon Koppelaars wrote a detailed and reasoned comment to that post. Since I admire Toon, getting his point of view on something that I wrote is a privilege for me, regardless if he agrees with me or disagrees (and just to be clear, it’s the latter this time). I think that having a public (and civilized) discussion – this time (more...)

Avoiding reinventing the wheel – use MULTISET EXCEPT to get set relative complement

Today in an application I stumbled upon a PL/SQL function created to return those elements of one nested table that did not exist in another nested table. Not a huge function, but still a bit of work and some thinking that had been done some while ago to compare the elements and create the desired output nested table.

The trouble is, that this functionality already natively exists in PL/SQL (and SQL) - the developer had (more...)

How to install MongoDB

This post shows the yum command to install the MongoDB packages on Linux. More on setup and use will follow.

You install the MongoDB package with the following yum command:

yum install -y mongodb

You should see the following log file, which may also show a missing mirrored site:

Loaded plugins: langpacks, refresh-packagekit
cassandra/signature                                         |  819 B  00:00     
cassandra/signature                                         | 2.9 kB  00:00 !!! 
mysql-connectors-community                                  | 2.5 kB  00:00     
mysql-tools-community                                       | 2.5 kB   (more...)

Performance Feedback Optionen in 12c aktivieren und deaktivieren

Christian Antognini erläutert in seinem Blog, welche Schwierigkeiten sich in 12c ergeben, wenn man das "Performance Feedback" aktivieren oder deaktivieren möchte. Zur Erinnerung: das Performance Feedback ist ein adaptives Feature und dient zur automatischen Prüfung, ob ein initial gewählter Parallelisierungsgrad tatsächlich vorteilhaft ist. Relativ harmlos ist bei der Konfoiguration noch der Faktor, dass sich der zugehörige Parameter in 12.1 OPTIMIZER_ADAPTIVE_FEATURES nennt, während er in 12.2 (bzw. auch in 12.1, wenn man den (more...)

OOW is just around the corner

Originally posted on HeliFromFinland:
I cannot believe how fast time flies! It has been an exceptionally busy year and that is the reason I have not had time to write blog posts either. I have been speaking in amazing events like BIWA Summit, APEX Connect, Riga DevDays 2017, OTNEMEA Tour in Baku and in Madrid,…

Too big to fail

There is this saying in the English language that something is “too big to fail”. It can refer to almost anything, a country, an initiative, a company, etc. What it tries to say is that, whatever the subject, is so big by now that there is simply no chance that it will ever go away … Continue reading "Too big to fail"

Demo App for REST enabled SQL

Getting Started  The new Oracle REST Data Services SQL over REST.  How to enable that is on my last blog post here: cURL Examples The simplest way to test this new feature out is with a curl command sending over the SQL. $ curl -X "POST" "http://localhost:9090/ords/hr/_/sql" \ -H "Content-Type:

Änderungen an v$diag_alert_ext in 12.2

Vor kurzem hat Markus Flechtner in seinem Blog auf einige Änderungen hingewiesen, die sich in 12.2 für die View v$diag_alert_ext ergeben haben, mit der man die Inhalte aus alert.log und weiteren Log-Dateien via SQL abfragen kann. Was sich leider anscheinend nicht geändert hat, ist, dass dieser Zugriff weiterhin deutlich langsamer erfolgt als der über die X$-View X$DBGALERTEXT. Dafür ist v$diag_alert_ext aber in 12.2 offiziell dokumentiert, was ihre Verwendung an Stelle des X$-Objekts (more...)

Optimistic Locking 6: which ORA_ROWSCN?

Continuing my series on using ORA_ROWSCN to achieve optimistic locking, let’s zoom in on ORA_ROWSCN itself. I've been asking myself this question:
  • ORA_ROWSCN can be maintained at the block level or the row level. What is the difference and which one should we use?

impdp mit metadata_only content führt zu gelockten Statistiken

Der Titel sagt eigentlich schon alles, was ich hier ausführen wollte: Frank Pachot weist darauf hin, dass ein auf Metadaten beschränkter Import automatisch die Statistiken lockt, um dafür zu sorgen, dass sie nicht vom nächsten Statistikerfassungslauf mit relativ uninteressanten 0-rows-Einträgen überschrieben werden. Auf diese Weise kann man mit einem metadata_only Import recht gut die Ausführungspläne des CBO vom Quellsystem nachvollziehen. Was den Herrn Pachot dabei ebenso irritiert wie mich ist, dass dieses Verhalten seit 10. (more...)

ORDS 17.3 Beta – Introducing REST enabled SQL

Download Got get it on the normal ORDS download page Versioning  First and most obvious is ORDS is now on the same versioning scheme as SQL Developer, SQLcl and Oracle Cloud.  That is <year>.<quarter>.<patch> and the same tail we've always had which is <julian day>.<HH24>.<MI>.  That makes this beta

Our Top 10 Sessions for Oracle OpenWorld 2017 – Forms 12c, Chatbots, Lift & Shift and More …

As the summer winds down, and fall begins to set in, at AuraPlayer it can mean just one thing ….Oracle OpenWorld preparations!

Here at AuraPlayer, we are feverishly planning for our participation with features in several sessions, events and of course our booth.  But we still wanted to take time to make sure all the Forms community (the needles in the OracleWorld haystack ) would know where to find the Forms content if (more...)

My Sessions Recommendations for JavaOne and Oracle Open World 2017

Good Day,

JavaOne, and Oracle Open World are 4 exactly weeks away.

Here are some sessions related to Java, JDBC, OJVM (database embedded JVM), JavaScript Nashorn (JavaSCript data access, JavaScript stored procedures), Apache Spark, Apache Hadoop, Apache Flink, Apache Beam that I'd warmly recommend.

JavaOne 2017 Sessions Recommendations

Big and Little Endian operating systems

Did you ever wonder or need to know which systems use big endian and which ones use little endian? Look no further, you can query it right out of the Oracle database: PLATFORM_NAME ENDIAN_FORMAT AIX-Based Systems (64-bit) Big Apple Mac OS Big Apple Mac OS (x86-64) Little HP IA Open VMS Little HP Open VMS Little … Continue reading "Big and Little Endian operating systems"

Optimistic Locking 5: “Read-consistent” SCN

Continuing my series on using ORA_ROWSCN to achieve optimistic locking, let's zoom in on the query API and the "read-consistent" SCN of the data it returns. I've been asking myself these questions:
  • How do we get read-consistent data in the query API if it does more than one SELECT?
  • How do we know the exact value of the "read-consistent" SCN?

Get Certified! #DataVault 2.0 Certification in the US

If you have been waiting to get your Data Vault 2.0 certification there are three sessions coming in the new few months right in the USA. Here is the list.

Provide access to #WebLogic DMS Spy Servlet for readonly users

For security reasons and to prevent the configuration drift it is recommendable to use read only for analyzing problems.

For read only access of configuration and logs WebLogic provides out of the box the group Monitors. Unfortunately you cannot access DMS Spy Servlet with this group, which is useful for analyse runtime values of the server. Only users which belongs to the Administrators group and therefore have full access can access DMS Spy Servlet and (more...)

PayWay interface

This is just to document how my system (which was built quite a few years ago) handles credit card payments via PayWay. The interface is rather dated and the way my system uses it is a bit hackish but for what it’s worth:

Step 1. On the server, generate a unique transaction reference, e.g. id123456

Step 2. On the server, request a token via HTTP Post:

Data (all one line):


Why you should never put objects into the SYSTEM or SYSAUX tablespace

Just because you can doesn't mean you should

Creating an Oracle Database Docker image

Run your Oracle database inside a Docker container