Riga Dev Days 2017, new experiences in many ways.

Riga Dev Days 2017


It has been a while since my last blog-post.
One of the reasons is my shift from closed to open source software, databases more specifically. More on that in a later blog-post.

The reason for already mentioning this is this strange hybrid (what a popular word, these days) situation that I am in at the moment.
Thanks to the super enthusiastic, flexible and tenacious organization-team of the Riga Dev Days, (more...)

Oracle Database standard Geo Location Support using Locator (included in every edition!)

imageMany databases have native support for locations en geodata – and determining distance and closest locations (within a certain perimeter). Oracle Database has the [Graph and] Spatial Option – that supports even the most advanced and exotic forms of location related data querying (including multidimensional shapes and probably relativistic effects); this option comes on top of Enterprise Edition and carries additional costs. What may be not as well know is the Locator functionality that is (more...)

Fastest creation of a Lean VirtualBox VM Image with Oracle Database 11gR2 XE, the Node.JS 7.x and the Oracle DB Driver for Node

For a workshop on Node.js I needed a VM to demonstrate and students try out the Oracle DB Driver for Node. I wanted a lean VM with the bare minimum: Oracle Database XE, Node, the Oracle DB Driver for Node and the Git client (for fetching sources from GitHub). I stumbled across the OXAR repository in GitHub (https://github.com/OraOpenSource/OXAR ) – Oracle XE & APEX build script along with images for popular cloud (more...)

ODA X4 – Migrating a database from ASM to ACFS

As promised ... Here's the post about migrating a database from ASM to ACFS on an ODA 4 - probably, this will work for newer ODA Servers as well


- Oracle Database Appliance machine, X4-<something>
- Software Release
- Prepared DB Software:,,

Story behind:

Task was, to create a new database of release for (more...)

Metadata Modeling in the Database with Analytic Views

Metadata Modeling in the Database with Analytic Views

12.2, the latest Oracle database release provides a whole set of new features enhancing various aspects of the product including JSON support, Auto-List Partitioning and APEX news among others. One of the biggest news in the Data Warehousing / Analytics area was the introduction of the Analytic Views, that as per Oracle's definition are

Metadata objects that enable the user to quickly and easily create complex hierarchical and dimensional queries on data (more...)

Oracle GoldenGate 101 at IOUG 17 and GaOUG TechDays 17 within two month

Losts have changed for me since my last blog post. A new job and new responsibilities, which will include presenting more at conferences on the conference circuit and a few roadshows that are planned in the near future.

Back in the fall of 2016, when most of the Call for Papers open, I had a great idea for introducing people to Oracle GoldenGate. This idea is walk everyone through the progression of replication technology from (more...)

Announcing Trivadis Performance Days 2017

Trivadis Performance Days 2017

It is a great pleasure to announce the next Performance Days! This year the event will take place the 13-14 September in Zurich.

Given that detailed information about the event as well as online subscription are available at https://trivadis.com/performance-days-2017, in this short post I limit myself to thanking and pointing out who the speakers that accepted my invitation are:


Reducing fetch time

Database query tuning is mostly about getting better plans. Mostly, but not always. Sometimes, the problem has nothing to do with the plan, and you might need to get a bit creative to find a solution. In this recent case a query was showing a decent performance when running from SQL Developer, but it took about 5 times longer to complete when running from R. The plan was the same, so I knew that it (more...)

Let’s start with Oracle Database 12c Release 2


Yes and now Oracle 12.2 is available (Linux x86_64) for download from OTN.


Let’s start with Installation and Setup ….



Oracle Database Result Cache Troubleshooting

I was troubleshooting an issue where the Oracle Database Result Cache did not get used when the RESULT_CACHE hint was specified inside a subquery. As the main query has a sysdate inside, the RESULT_CACHE Hint can not be specified for the main query, but only for the subquery.

SELECT SQ.*, sysdate FROM
(SELECT * FROM tableX, ....) SQ;

When using “/*+ RESULT_CACHE */ inside of Subquery, result cache was not (more...)

Long-running INSERT

On one of the databases I’m looking after (, Solaris, non-RAC), several different INSERT statements (all into tablespaces with manually managed segments) suffer from occasional hiccups. The symptoms are always the same: in one of the sessions, the INSERT gets stuck doing lots of single-block I/O against one of the indexes on the inserted table, and if other sessions are running similar INSERTs, they hang on enq: TX – index contention. The (more...)

What new?


Interesting news about the coming Oracle 12 Release.

Release Schedule of Current Database Releases (Doc ID 742060.1)

Take a look :-)

#Oracle cutting in inspiration and new business?

Over the many years Oracle has been leading the database world, I guess they are now taking something of a wrong turn.
Let me briefly fill you in on my thoughts.

Basically I see two “minor” shifts that are significantly indicative of this:

  1. Oracle Standard Edition 2
  2. Oracle ACE Program

Okay, so you might think I am crazy, but let me try to explain.

Oracle Standard Edition 2

Sometime last year, the long expected, (more...)

Explicit Semantic Analysis in Oracle 12.2c Database

A new Oracle Data Mining algorithm in the Oracle 12.2c Database is called Explicit Semantic Analysis.

[The following examples are built using Oracle Data Miner 4.2 (SQL Developer 4.2) and the Oracle 12.2 Database cloud service (extreme edition) ]

The Explicit Semantic Analysis algorithm is an unsupervised algorithm used for feature extraction. ESA does not discover latent features but instead uses explicit features based on an existing knowledge base. There (more...)

#DOAG2016, definitely a crazy week.

#DOAG2016, the largest Oracle Community gathering in Europe. Taking place in Nuremberg, at the Nuremberg Convention Center NCC, one of the more impressive places to hold such a conference, towering 4 stories high, with a big central atrium!!
It is a huge effort to get all of this together!

In this blog-post I want to highlight some of the crazy things I experienced this week… And… I did try to follow my own schedule (more...)

tnsnames.ora, keeping your connections under control

There are a lot of ancient things that prove to be still valuable today.
Recently I came across something, which I thought I could or should share here.
Your tnsnames.ora file, centrally managed in a distributed environment.

This solution applies whether you are working with the Oracle Instant Client or with the full blown setup of the client software.

Imagine you have an environment with a reasonably big bunch of PC’s. Wether you are (more...)

What’s the Difference between Row Migration and Row Chaining?

In Oracle Database migrated and chained rows are often confused. In my opinion, this is for two main reasons. First, they share some characteristics, so it’s easy to confuse them. Second, Oracle, in its documentation and in the implementation of its software, has never been very consistent in distinguishing them. So, it’s essential to understand the differences between the two.

When rows are inserted into a block, the database engine reserves some free space for (more...)

Problems with big SGAs (>200G) on Linux

I recently had an issue where a database with 240GB SGA (1 huge shared memory segment) configured with hugepages on a system with 512G RAM was suddenly becoming instable and new logons were denied with these error message:

ORA-01034: ORACLE not available
ORA-27123: unable to attach to shared memory segment
Linux-x86_64 Error: 22: Invalid argument
Additional information: 2667
Additional information: 1736718
Additional information: 215016800256

This was strange because ipcs -a showed all shared memory segments (more...)

OTN Appreciation Day: PL/SQL

We are posting these blog posts today as part of the OTN Appreciation Day, a celebration for the Oracle Technology Network as suggested by Tim Hall, inspired by Debra Lilley.

The mission was not too hard: write about your favorite bit of Oracle Technology.

As a developer and a core-tech DBA and APEX enthusiast… the choice was easy! PL/SQL (apart from how it is pronounced or even written ;-)!

Why? Easy!

Not just because (more...)

#OOW16, San Francisco, looking back

In this post I just wanted to highlight a few things that have lingered with me since the 2016 Oracle Open World Experience.

Persistent DRAM
Now, here, being at home, I must admit that I cannot find very much documentation about this, but it got me thinking… A little paradigm-shift, where computers actually wouldn’t need moving parts anymore (ie. disks of any kind). Create devices that use these memory structures, quite possibly combined with flash-disks, (more...)