Databases at CERN blog

Custom Flume sources for ingesting data from database tables and log files

On our way to build a central repository that stores consolidated audit and log data generated by the databases, we needed to develop several components that will help us to achieve such purpose. In this case, we will be talking about two custom sources for Apache Flume that have been developed in order to collect data from databases tables and (alert & listener) log files. Both these sources are implemented in a generic way, without any project dependency, so they can be used for any other project and the code is publicly accessible.

Offline analysis of HDFS metadata


HDFS is part of the core Hadoop ecosystem and serves as a storage layer for the Hadoop computational frameworks like Spark, MapReduce. Like other distributed file systems, HDFS is based on an architecture where namespace is decoupled from the data. The namespace contains the file system metadata which is maintained by dedicated server called namenode and the data itself resides on other servers called datanodes.

This blogpost is about dumping HDFS metadata into Impala/Hive table for examination and offline analysis using SQL semantics

Java web application based on OAuth2


Last week I've investigated how does OAuth2 protocol works and developed a Proof of Concept (PoC) in Java. In this post I would like to show you how effortlessly develop simple client-server application using OAuth 2.0 standard for authorization of protected resources placed on a server.

Before we start developing our first secured web application with OAuth2 let's understand how it works.

What is it and how does it work?

Experiences of Using Alluxio with Spark


Alluxio refers to itself as an "Open Source Memory Speed Virtual Distributed Storage" platform. It sits between the storage and processing framework layers in the distributed computing ecosystem and claims to heavily improve performance when multiple jobs are reading/writing from/to the same data. This post will cover some of the basic features of Alluxio and will compare its performance for accessing data against caching in Spark.


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