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Modeling

Visual Data Vault by Example: Modeling in the Accounting Industry

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With the advent of Data Vault 2.0, which adds architecture and process definitions to the Data Vault 1.0 standard, Dan Linstedt standardized the Data Vault symbols used in modeling. Based on these standardized symbols, the Visual Data Vault (VDV) modeling language was developed, which can be used by EDW architects to build Data Vault models. The authors of the book “Building a Scalable Data Warehouse”, who are the founders of Scalefree, required a visual approach to model the concepts of Data Vault in the book. For this purpose, they developed the graphical modeling language, which focuses on the logical aspects of Data Vault. The Microsoft Visio stencils and a detailed white paper are available on www.visualdatavault.com as a free download.

Hubs in Visual Data Vault

Business keys play an important role in every business, because they are referenced by business transactions and relationships between business objects. Whenever a business identifies and tracks business objects, business keys are used throughout business processes. This is one of the reasons why Data Vault is based on the business keys. In Data Vault models, business keys are stored in hub entities. The challenge is to identify the business keys which represent a business object uniquely. That can be just one business key, but also a composite key or a smart key. The first image shows a hub with only one business key attribute:

Here, the attribute Invoice Number is sufficient to identify the invoice. No other attribute is required (such as the invoice year). In other cases, it is not as easy Read More

The Value of Non-Historized Links

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When Dan Linstedt, co-founder of Scalefree, invented the Data Vault, he had several goals in mind. One of the goals was to load data as fast as possible from the source into a data warehouse model, process it into information and present it to the business analyst in any desired target structure.

For simplicity and automation, the Data Vault model exists only of three basic entity types:

  1. Hubs: a distinct list of business keys
  2. Links: a distinct list of relationships between business keys
  3. Satellites: descriptive data, that describe the parent (business key or relationship) from a specific context, versioned over time.

Now, as we always teach (and sometimes preach): you can model all enterprise data using these three entity types alone. However, a model using only these entity types would have multiple disadvantages. Many complex joins, storage consumption, ingestion performance and missed opportunities for virtualization.

The solution? Adding a little more nuts and bolts to the core entity types of the Data Vault in order to cope with these issues. One of the nuts and bolts is the non-historized link, also known as Transaction Link:

In this example, Sales is a non-historized link that captures sales transactions of a customer, related to a store. The goal of the non-historized link is to ensure high performance on the way into the data warehouse and on the way out. Don’t forget, the ultimate goal of data warehousing is to build a data warehouse not just model it. And building a data warehouse involves much more than just the model: it requires people, processes, and technology. Read More