DB Nemec



Database and Data Warehouse Solutions

Miscellaneous SQL Themes

ANSI Join Syntax

Starting with 9i there is an alternative way to (+) .... (see here)

Partitioned Outer Join

A feature for "gap fillers" in 10g. A discussion and further links can be found here


Read the true story of a select with ROWNUM=1 that caused more than 100K PIO

Analytic Functions

A summary of the most important analytic functions using a simple product sales example

How to Get Partition Name

How to assign the partition name for each row in the table?

Sense of Humour

Does Oracle have a Sense of Humour?

Synthetic Analytic

More on analytic functions in Oracle

Happy New Peek

Sometimes the execution plan is only a plan. A little demonstration that bind variable peek phenomenon is not limited to an existence of histogram. A peek on a partitioned table may change the plan in unpredicted way …

How to Change the public IP Address in an Oracle RAC

This task is trivial, but not always… Read more here

Execution Plan Flip

An example of an execution plan flipping randomly after re-gathering optimiser statistics.

Here the updated version of the example that works in 11g.

Groovy in Database

How to integrate Groovy Script in Oracle Database and call them from a select statement.


Adding a missing No-Rows-Query for Include-Xml in the Oracle XSQL servlet


Reading with WHERE Clause

SQL Injection allows read arbitrary granted data modifying the WHERE clause

Sampling Time Series Data

How to get coarse grained sample without sorting

Time Dimension

How I Create a Time Dimension with Surrogate Key – and Through it Away Immediately

Rolling Window

Using interval partitioning to implement rolling window

Adaptive Cursor Sharing

Friend or Foe?  


XML Processing Using JDBC  

Materialized View Refresh

Just in Time Refresh Mode of Materialized Views  

UKOUG 2012

Cache and Query – presentation


Creating a JSON from a hierarchical query (connect by)

Real World Performance Tour

I attend Real World Performance Tour 2015 in Vienna


An example of Multi Dimensional Scaling in R


Using MD5 to compare tables


Basic approach to the visualisation of relations in a relational database