16. 08. 2018.

Exadata / Linux crash – capturing kernel dump on Linux systems

This article has been motivated from real life issue experienced on Exadata system running a few dozen of Oracle databases. I have already written about Exadata shortcoming in one of previous articles where I stressed that one of the main disadvantages of Exadata machine is non-existent virtualization technology. Oracle recognizes Oracle VM as the only […]

27. 05. 2018.

Exadata shortcomings Part 2

Flexibility   Flexibiliy is a weak point in case of Exacloud also that I tested last year (you can found on this site). Exadata is delivered with pre installed and configured SW and 2 node cluster. It’s true that you can destroy it and customize, but that’s not the point (in that case it’s much […]

27. 05. 2018.

Exadata shortcomings Part 1

It’s very difficult to write about Exadata Appliance, the famous jewel in the Oracle offering, machine that combine HW and SW that are engineered to work together. There is no point to repeat what you can already know or find in books, web or wherever. On the other side, rarely you can find that someone […]

09. 10. 2017.

Exadata part V – table & column compression

Exadata has columnar compression which is a very different from the regular table compression available on non Exadata Oracle databases. While normal compression algorithms (basic, OLTP etc.) are all block based, columnar compression is Exadata specific and is based on column instead of blocks. Here I want to show compression efficiency and time needed to […]

09. 10. 2017.

Exadata part IV – Exadata in Action

Here I’d like to show performance benefits of Exadata on complex, realistic SQL. Previous queries are more or less for toy, where the only purpose is to clearly show some feature/concept and what performance benefits you expect from it. The query I use in this article is known to be problematic on one of production […]

09. 10. 2017.

Exadata part III – reading from large partitioned table

This article is third in series about my experiences with Exadata database machine. Results in previous two articles are really great for Exadata. Here I’ll prove that there could be cases where Exadata is actually slower than Oracle database running on commodity hardware. Test case is serial reading from large partitioned (and sub partitioned) table […]

09. 10. 2017.

Exadata part II – parallel read

In this article I’ll cover parallel read from tables created in the first part that you can find here. As Exadata has many cores in all configurations, this is where I expect it has to shine. Let’s check it. 1. select /*+ parallel */ count(*) from tdh_nopartitions_normal; 12,27 sec 2. select /*+ parallel */ count(*) […]

09. 10. 2017.

Exadata part I – serial read

This is the first article about my experiences with Exadata machine during the 3 month period. I’ll try to avoid all commercial hypes and try to present the most valuable database machine as much realistic as I can. I’ve took 3 – 4 books that covers material related to Exadata in scope of preparations to […]

09. 10. 2017.

Exadata Exacloud service review

Recently I had a great opportunity to test Exadata Exacloud service for a 3 month period. Although I had already tested various Oracle’s Cloud services, this is probably the crown in the Cloud offering. Here I don’t want to write about what is already known. Instead I want to share my own experience with the […]