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In our ongoing series, CEO Michael Olschimke a question from the audiance:

“What is the recommended way for Hashing? In the case of an optional relationship, should we first replace the NULL value with the default value before hashing? What is the reason for this? Should we include the BK of parent (hub/link) in calculation of HashDiff? The above was mentioned in your book ‘Building a scalable datawarehouse with data vault 2.0’ but other blogs emphasize a loading code for a satellite that compares the latest HashDiff per HashKey (even if BK is included in HashDiff). Is there a specific reason?”

Specifically, the discussion delves into whether it is advisable to replace NULL values with default values before hashing in the context of an optional relationship. The rationale behind this practice and the potential inclusion of the BK of the parent (hub/link) in the calculation of HashDiff are explored.

This topic was previously highlighted in Michael’s book ‘Building a scalable datawarehouse with data vault 2.0’, but contrasting perspectives from other blogs advocate for a loading code approach for a satellite that considers the latest HashDiff per HashKey, even if the BK is included in the HashDiff.

Michael sheds light on the significance of Hash Key and Hash Diff in this discussion.

Meet the Speaker

Michael Olschimke

Michael has more than 15 years of experience in Information Technology. During the last eight years he has specialized in Business Intelligence topics such as OLAP, Dimensional Modelling, and Data Mining. Challenge him with your questions!

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To support the creation of Visual Data Vault drawings in Microsoft Visio, a stencil is implemented that can be used to draw Data Vault models. The stencil is available at www.visualdatavault.com.

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