Tagged: Time variance

1

When is a change a ‘change’?

This is a post that touches on what I think is one the essential best-practices for ETL design: the ability to process multiple changes for the same key in a single pass. This is specifically relevant for typical ETL processes that load data to a time-variant target (PSA, Satellite, Dimension etc.). For non-time variant targets (Hubs, Links etc.) the process is a bit easier as this is essentially built-in the patterns already :-). In a given...

 
0

Creating Data Vault Point-In-Time and Dimension tables: merging historical data sources

Beyond creating Hubs, Links and Satellites and current-state (Type 1) views off the Data Vault, one of the most common requirements is the ability to represent a complete history of changes for a specific business entity (Hub, Link or groups of those). If a given Hub has on average 3 or 4 Satellites, is it useful at the very least to see the full history of changes for that specific Hub across all Satellites. How to...

 
3

Zero records, time-variance and point-in-time selection

While finalising the posts for the overall Data Vault ETL implementation I have also started thinking about how to document the next steps: the loading patterns for the Presentation Layer. From here on I will refer to the Presentation Layer, Data Marts and Information Marts simply as ‘Information Marts’. This reminded me that I haven’t yet properly covered the ‘zero record’ concept. This is a timely consideration: the whole reason that zero records exist is to make the...

 
2

A brief history of time in Data Vault

To quote Ronald Damhof in yesterday’s twitter conversation: ‘There are no best practices. Just a lot of good practices and even more bad practices’. Sometimes I feel Data Vault lacks a centrally managed, visible, open forum to monitor standards. And, more importantly, the evolution of these standards over time. And, even more importantly, why these standards change over time. It varies (in space and time) where sensible discussions regarding these standards take place, but lately...