Databases at CERN blog

A Summer at CERN: Evaluating OpenStack Trove as DBaaS Solution

I have been one of the 23 students participating in the CERN openlab summer student programme this year. Like two of my fellow students in the database group, Sneha and Anti already did, I want to share some insights into the project I worked on and in general about my experience with the summer programme. Thus, the post is divided into a general part and a technical part, which will sum up what I did with OpenStack and its component Trove.

Importance of testing yours backup strategy

Most of you for sure know, that ability to restore data in case of failure is a primary skill for each DBA. You should always be able to restore and recover data you’re responsible for. This is an axiom. To be sure, that you’re able to do it, you should test it on regular basis. There is of course possibility to use some Oracle features, like backup ... validate or restore ...

SystemTap into Oracle

Topic: This post is about using SystemTap for investigating and troubleshooting Oracle RDBMS. In particular you will learn how to probe Oracle processes and their userspace functions. These techniques aim to be useful as well as fun to learn for those keen into peeking under the hood of the technology and improve their effectiveness in troubleshooting and performance investigations.


Indexes in Oracle DB part 2

In my first post about indexes I promised that more in this topic will follow up and here it is... This series of articles is based on observation how developers fail to correctly implement indexing in their applications based on Oracle and aims to provide guidelines on how indexes should be used. Today let’s focus on index scans. Understanding how their work might be very helpful in planning the indexing strategy!

Backups in Data Guard environment

Physical standby databases seem to be ideal candidates for offloading backups from primary ones. Instead of "wasting" resources (unless you're already using Active Data Guard for example), you could avoid affecting primary performance while backing up your database, especially if your storage is under heavy load even during normal (user- or application-generated) workload. So, if you're seeking for good reasons to convince your boss/finance department/etc.

Scaling up Cardinality Estimates in

Topic: Counting the number of distinct values (NDV) for a table column has important applications in the database domain, ranging from query optimization to optimizing reports for large data warehouses. However the legacy SQL method of using SELECT COUNT (DISTINCT <COL>) can be very slow. This is a well known problem and Oracle provides a new function APPROX_COUNT_DISTINCT implemented with a new-generation algorithm to address this issue by providing fast and scalable cardinality estimates.




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