HASHDIFF – Data Vault 2.0

Data Vault Anti-pattern: Including Business Keys in the SAT HASHDIFF

Saqib Ali | May 2, 2022

A Satellite contains the descriptive attributes of a Business Key. As such, a Satellite HASHDIFF should be constructed using the only the descriptive attributes of the Business Key. The Business Key, itself, should not be part of the Satellite HASHDIFF. Note: While it is a common practice to include the Business Keys in the SAT …

Data Vault Anti-pattern: Adding column to the middle of the hashdiff

Saqib Ali | May 1, 2022

All new columns added to the SAT must be added to the end of the Satellite HASHDIFF. Dan Linstedt describes this as, “Columns that are NULL and at the end of the table are not added to the input of the hash function”[1]. Basically this pattern prevents reloading of the entire dataset when there is …

Data Vault Anti-pattern: Using varchar to store the HashKeys and HashDiffs

Saqib Ali | February 24, 2022

Why would you do that? HashKeys and HashDiffs are binary generated using a hashing algorithm like MD5 or SHA-1. Just store them as binary and effectively halve your storage and double your I/O! No need to convert them to the Char to store them as Varchar.