Cognitive loadtheory, developed in the 1980s by John Sweller, is an important concept in learning enforcement. The theory is applied in school education. Cognitive load refers to the used amount of working(human) memory resources – the limited capacity that can hold information temporarily. To quote Sweller; “the human brain can only process a small amount of new information at once, but it can process very large amounts of stored information. The average person can only hold about four ‘chunks’ of information in their working memory at one time.”
Rather than bombard the student with all information at one time, introducing a new concept is performed by limiting the new information into digestible “chunks”. Further… “information is stored in the long-term memory in ‘schemas’, which provide a system for organising and storing knowledge.”
Figure 0 1 Lifted from Department of Education, Cognitive Load Theory in Practice (NSW Government)
Once new information is learnt the information is reinforced and as the student is taught new information that information already has a base to build from. Gradually as the student becomes more proficient in the subject matter, independent problem-solving is introduced.
Let’s illustrate by way of an example … by making beer!
“Brewers make wort. Yeast makes beer”- Dave Miller
- Mashing – the process of mixing malted grains (the grain bill) into a boil. Malted grains contain the starch and enzymes that, through boiling, is encouraged to depart from the rest of the grain. The starch is needed for the hungry yeast.
- Lautering & Sparging – rinsing of the mashed grain bed to extract as much of the starchy sugars from the grain as possible. The additional water used to rinse the half-spent grain is added to the wort and the spent grain itself is discarded as fertilizer and animal feed.
- Boiling – at different temperatures (typically around 100C / 212F) and lengths of boils (60-90 minutes), bittering, flavouring and aroma hops are added to the wort which at the end of the boil becomes a syrup ready for the hungry yeast – the wort.
- Fermenting – once the boil has completed the wort is rapidly cooled to a temperature to suit the type of yeast you will use that will eat the starch and produce alcohol as a by-product. 11-15 Celsius (51.8 – 59 Fahrenheit) for lager yeast and 17-25 Celsius (62.6 – 77 Fahrenheit) for ale yeasts. The wort is left alone in an airtight tub for 3 to 10 days.
Variance in the steps, ingredients, temperature and time is what produces different beers. For instance, a Munich Dunkel will use lager yeast, some roasted malts and Hallertau hops, whereas an Indian Pale Ale (IPA) can use Belgian ale yeast, Pilsner malts and Saaz hops. There are more things you can do tamper with the flavour, aroma, colour and clarity of the beer however the core four steps remain the same.
This is not too different than learning data vault for the first time (or any other skill for that matter); first we establish the core “chunks”, and the initial learnings are reinforced. New information is built upon those learnings and the cycle continues where learning is gained through coaching and experience. Let’s start with the first “chunks”:
- When modelling a data vault we start with understanding what the business entities that matter to the business are; like conceptual modelling, we learn how the business sees their enterprise. These entities are modelled as tables called “Hub tables” and contain a unique list of business entity identifiers that represent a thing, entity or object. The identifier values are the immutable unique key that for the life of the entity in the business process does not change. That key will forever tie to that business entity.
- Naturally after identifying the things, objects or entities we wish to model it is important to understand how they relate to each other; this is the unit of work and in the data vault is represented in a “Link table”. A Link table captures the business processes present in the enterprise as the relationships between business entities is engrained in these Link tables. One-to-one, one-to-many and many-to-many relationships are stored in a link table structure, this could be a relationship between two or more entities but may be between one or more hubs as is the case of hierarchical relationships or multiple business keys representing the same entity!
- Finally, when it comes to the descriptive content about the business entity or relationship we store that content as “Satellite tables”. A satellite table may describe a single business entity, object or thing and another satellite may describe the relationship between two or more entities.
Figure 0‑3 model for the fictitious brewery
Staff take orders from distributors and each order may have multiple line items and each line item is describing the quantity of products. Products are sold in one of two types of units: either as bottles or as kegs. For bottles, the minimum spend is eight cases (24 bottles in each case) or four kegs. Each product has ingredients which are common across most of the products, the ingredients used in a batch are used to produce products and we also track who supplies the ingredients, the frequency and in what quantities. Of course, the overall model would be much larger but we’re not trying to boil the ocean in our use case, we want to track the history and efficiency of our supply chains to beer output. On to our modelling process!
- Business entities
- Staff? Yes, we track name, contact details, address and so on. Details about the staff can change and change often. In the enterprise ontology we have salary details, performance and so on, each tie to a staff id (business key).
- Distributor? Yes, these details can change. We track their address and tie them to a distributor id (business key).
- Order? Yes, each order is tracked until fulfillment against an order number (business key) is complete.
- Order-line-item? No, a line-item has no history, and order details are tracked to the order id (can be a dependent-child key).
- Product? Yes, we use stock id (business key) and track how much stock we have, but products themselves are referenced from a reference table by product code.
- Inventory/ingredients? Yes, each item is tracked by smart key with parts of the key denoting what type of item it is.
- Batch? Yes, each batch has a batch id (business key) and we track where the batch is in the brewing process (mash, lauter, boil, fermentation and bottling/kegging).
- Supplier? Yes, where we purchase ingredients, gas and parts which we track with our own supplier id.
2. Relationships or unit of work
- An order is placed by a staff member for a distributor. An order has line items with quantities of each product. Although the line-item itself is an id for a different order the same line-item id will more than likely be describing a different product and quantity, it is a weak key (dependent-child id).
- Staff is hierarchical in the sense that we have junior sales staff that report to account managers, who in turn report to a sales director. Staff is not limited to sales either, we have staff who are involved in the brewing process as well as security staff.
- Brewing staff are involved in placing orders for ingredients and supplies for operation and maintenance, including water and electricity to run the brewing process.
3. Descriptive content
- Staff content must be split because we capture personally identifiable information (PII) and confidential data.
- Unit of work descriptors are tracked for making orders, order fulfillment, purchasing supplies for inventory, and inventory used in a batch to produce products.
- Descriptive content is also tracked on individual business entities such as contact details, stock movement and so on.
That’s it! Modelling in data vault is down to three steps, all other considerations to the data vault model build upon those three-core model types: hubs, links and satellites. Data Vault 2.0 adds to the modelling of data vault by discussing the three pillars of data vault, architecture, methodology and modelling.
- Learn the standards and you can apply them to any jurisdiction or data platform, and you can be safe in the knowledge that the data vault model will flex as the enterprise and industry flexes.
- Agile principles apply, although there are so many variances (ingredients) to delivering a data vault; remembering how to design and build the base artefacts will get you going. You are capturing the enterprise ontology in a data vault therefore having a business analyst and subject matter experts to help you develop the data vault model is vital.
- To gain the confidence on delivering a data vault there are options available on the market:
- Get training through a certified training provider, and/or
- Get onsite coaching, and/or
- Get your data vault reviewed
Fun Fact: The old medieval name for yeast (because its properties for making bread and beer were shrouded in mystery) was known as Godisgoode.
Author: Patrick Cuba
Patrick has nearly 20 years working on data-inspired problems utilizing his experience and he has embraced Data Vault 2.0. He works by understanding the business before innovating the technology needed to ensure that his data-driven delivery is agile and automated. He is Data Vault 2.0 certified and regularly contributes to Data Vault Alliance.