Exasol

Exasol introduced Partitioning in version 6.1. This feature helps to improve the performance of statements accessing large tables. As an example, let’s take these two tables:

Your BI users complain about slow performance of their analytical queries? Is this your Status Quo?

• Exasol
• TOI

After having installed the latest VirtualBox version, an ISO file with the latest Exasol version has to be downloaded. The machine hosting VirtualBox should have at least 16 GB RAM and 80 GB free disk space in order to run a 2+1 Cluster with 3 data nodes and one license server. I’m doing it on my Windows 10 notebook.

Exasol doesn’t need much administration but getting distribution right matters

Exasol uses a clustered shared-nothing architecture with many sophisticated internal mechanisms to deliver outstanding performance without requiring much administration. Getting the distribution of rows between cluster nodes right is one of the few critical tasks left, though. To explain this, let’s say we have two tables t1 and t2:

The result of a query can be cached in Exasol to the effect that repeated identical queries complete in no time. This feature has been introduced in version 5 and is enabled by default.

SQL_EXA> select session_value,system_value  from exa_parameters where parameter_name='QUERY_CACHE';
EXA: select session_value,system_value  from exa_parameters where parameter...

SESSION_VALUE        SYSTEM_VALUE
-------------------- --------------------
ON                   ON

1 row in resultset.

The Query Cache can be (de-)activated on the session level as well as on the system level.

This little script displays some useful meta-information:

https://uhesse.files.wordpress.com/2018/05/exasol_logo.png?w=150 150w" sizes="(max-width: 161px) 100vw, 161px

https://uhesse.files.wordpress.com/2015/10/helps.png?w=600&h=558 600w, https://uhesse.files.wordpress.com/2015/10/

https://uhesse.files.wordpress.com/2015/10/helps.png?w=600&h=558 600w, https://uhesse.files.wordpress.com/2015/10/

This article gives a more detailed view on the Exasol Cluster Architecture. A high level view is provided here.

Exasol Cluster Nodes: Hardware

An Exasol Cluster is built with commodity Intel servers without any particular expensive components. SAS hard drives and Ethernet Cards are sufficient. Especially there is no need for an additional storage layer like a SAN.

See here for a list of Exasol Certified Servers.