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data warehouse

We build a data warehouse from the General Query Log

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The design of a data warehouse differs from relational design. Data warehouses are often designed according to the concept of the star schema.

When building a data warehouse, you usually put the cart before the horse:

Wir bauen uns ein Data Warehouse aus dem General Query Log

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Das Design eines Data Warehouses unterscheidet sich vom relationalen Design. Data Warehouses designt man oft nach dem Konzept des Star Schemas.

Üblicherweise zäumt man beim Bau eines Data Warehouses das Pferd von hinten auf:

Data Warehouse Design

This is my cheat sheet for dimensional modelling design techniques of a data warehouse (DWH) according to Kimball/Ross.

Dimensional Design Process (p. 38 ff.)

  • Select the business process.
  • Declare the grain (what a single fact table row represents).
  • Identify the dimensions.
  • Identify the facts.

Dimension Tables (p. 46 ff., p. 62 ff.)

who, what, where, when, why and how


Query performance comparison between MariaDB ColumnStore and other Storage Engines

Storage Engines like InnoDB, Aria and MyISAM are Row Stores. They store rows one after the other in blocks or even directly in a single file (MyISAM). On the other hand a Column Store like MariaDB ColumnStore stores all the same attributes (columns) of the rows together in chunks.

This is how the table sales_fact looks like:

Do not trust other peoples benchmarks!

Because they do NOT reflect your problems.

One of our customers upgraded last month from MariaDB 10.2 to MariaDB 10.5. In the same change he also converted all his data warehouse (DWH)/BI tables from MyISAM to Aria. An all this, naturally, without testing. And it miserably failed! And then we were under heavy time pressure to make things working again...

What has changed:

Wir bauen uns ein Data Warehouse mit MySQL

Unsere Folien zum Vortrag Wir bauen uns ein Data Warehouse mit MySQL stehen jetzt zur Verfügung unter Präsentationen.

MySQL pluggable Storage Engines (SE)

One of the big advantages of MySQL is its concept of Pluggable Storage Engines. This means you can choose the most optimal Storage Engine for your needs. This also has a disadvantage: You have to know what you are doing...

If you need some help deciding which is the right Storage Engine or even strategy for you or if you want us to make an independent and vendor neutral comparison of those Storage Engines consider our FromDual Consulting Services!


The battle against Oracle is probably over but has the real war begun yet?

According to different sources from the web the decision about the Oracle - Sun merger has been approved by the European commission soon. So at least in the West it is clear what is going on. Let us see what the East decides... [ 1 ], [ 2 ].

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