External tables in Oracle
External tables allow someone to store data in a file while these files are shown as tables within Oracle. So, we have a two sided object – on one hand […]
Analysing JSON and database tables in Spark
In a previous note, I showed how CSV files can be analysed. One may use the same technique to analyse JSON files or tables in a database. First, analysing JSON […]
Processing CSV files in Spark
It is possible to process CSV files in Spark as if these files are tables. That looks very promising: reading a file, translating the file into something that can be […]
Install Spark on windows
I found a beautiful YouTube movie that showed how Spark can be installed on windows. I found this on https://www.youtube.com/watch?v=WlE7RNdtfwE . The movie provided a clear guide how to this […]
Useful Scala Programme
I saw a small Scala programme that allows you to calculate subtotals. The idea is that a flat file is provided with a name and a subtotal. A given namen […]
The tango between Hive and Impala
An interesting tango exists between Hive and Impala. The situation is as follows. Hive acts as an layer upon map reduce. It provides an interface whereby table definitions can be […]
Joining files by Pig
In the previous post, we used scala to merge two files. The interesting feature is that scala bypasses Mapreduce. Pig uses Mapreduce. If we undertake the same example, we will […]
Joining files by Scala
In this note, I will provide another script to join two files. The files are foo and bar. They contain lines whereby the elements are separated by a bar (|). […]
Flume used for logs
In an earlier post, I showed how one may send a stream via netcat to hdfs using flume. Another possibility is to set up a stream that is received by […]
Datamodelling in Hadoop
Before data modelling in Hadoop can be discussed, one needs to realise that Hadoop is about files. It is not about tables and relations – it is the files that […]