Category: Allgemein

In the Hadoop world, one may encounter AVRO files quite often. AVRO file can be used in more or less the same way as text files. They can be read, stored and written out. However, the AVRO files are binary files that make them difficult to read. However, help is there. I downloaded the avro-tools-1.8.2.jar…

Today, I played a bit with mounting external drives. Boy, that was more difficult than I thought. The situation was a follows. I had a linux desktop and I wanted to use network resources. I have a NAS, a samba drive and a few windows shares. A the end of the day, I only got…

Sqoop is used in an Hadoop environment to load data from a relational database upon an Hadoop platform. I have installed an Oracle 12.2 database. I tried to load data from that database to Hadoop. To do so, one needs to install a java jdbc driver to be able to access that database. For Oracle…

Cloudera Manager is a great tool to install a Big Data platform. I worked with this tool and let me share some findings. I realise that we have only a limited range of platforms that can be used to install the Cloudera Manager upon. I started with Ubuntu 16.04. In a first attempt, I used…

Yesterday I found a very nice script that allows processing records in a target table with a SCD-2 mechanism. The script is very elegant. It contains several logical steps that are knitted together in one SQL statement. Th mechanism of SCD2 is as follows. First, a comparison is made between a source table and a…

I want to show the usage of an explain plan in Oracle. This will be shown in Oracle 12c. I will create a table and a sql statement. This sql statement will be analysed in a so-called explained plan that shows how Oracle will process the query. To do so, I first created a big…

I regularly install Oracle. In most cases, such installation is straightforward. Start the setup, provide a few data and click next, next, and next. Half an hour later, one has a fresh instance running. However, I recently got an error when installing Oracle 12c, version 2: installation was stopped as an error was encountered. This…

Oracle has a wonderful spatial module. The spatial data are stored in a database as so-called SDO_GEOMETRY data type. The data in such field look like: (MDSYS.SDO_GEOMETRY(2001,90112,MDSYS.SDO_POINT_TYPE(121235,484926,NULL),NULL,NULL)). In this structure, we see the so-called SRID. This SRID is here 90112. This indicates how a geographical location can be translated in coordinates. In this case we…