5 Indicators That Your Knowledge is Modeled Poorly | by Matthew Gazzano | Jun, 2023

Frequent Challenges In The Cloud period

Photo by Jan Antonin Kolar on Unsplash

With the growth of cloud know-how and low-cost storage prices previously decade, many organizations have amassed considerably bigger volumes of knowledge than beforehand conceivable. The pay-as-you go mannequin supplied by many cloud knowledge warehouse suppliers (AWS, GCP, Azure) has decreased the necessity for up-front capital sources and consideration of digital infrastructure.

The excellent news is that this finally makes knowledge science efforts extra accessible for many organizations.

The unhealthy information is that Knowledge Lakes are turning into extra like Knowledge Swamps.

What’s Knowledge Modeling? And What Challenges Encompass it?

It is usually tough for Knowledge Engineers to speak the worth of a well-modeled ecosystem to higher administration. It’s because all that’s seen to stakeholders are the BI instruments and predictive fashions that get offered. Nonetheless, poorly modeled knowledge causes main setbacks to analytics groups from an information governance perspective. This inevitably slows down workflow, introduces repetitive duties, decreases reporting accuracy, in addition to many different unfavorable unintended effects.

Defining “Properly-Modeled” knowledge is a subject of its personal. However you may consider it by the next ideas in your Knowledge Warehouse:

  • A transparent sample exists on the right way to discover knowledge tables that relate to enterprise entities.
  • An intentional / recognized modeling method is used, similar to a dimensional mannequin, entity relationship mannequin, knowledge vault, and so forth.
  • Desk and discipline naming conventions are constant, nicely documented, and maintain enterprise worth.

It must also be famous that there’s a holistic and multi-system strategy to knowledge modeling. It begins in your OLTP (On-line Transaction Processing) system, which is the place knowledge will get initially recorded. Listed here are some examples:

Ideally, your knowledge must be normalized in 3rd normal form when collected by means of a supply system. Then it must be ingested into an analytics atmosphere, in any other case often known as an OLAP (On-line Analytical Processing) system the place an analytical modeling method is utilized. Within the context of this text, the OLAP system is synonymous with a cloud knowledge warehouse. However OLAP methods may also embrace independently hosted instruments like SQL Server, MySQL, or PostgreSQL.

Whereas knowledge analysts and knowledge scientists solely work together with the OLAP system, a corporation’s knowledge modeling technique must consider each OLTP and OLAP to be sustainable.

1.) Tribal Data is Required to Perceive The place to Discover Knowledge

To ensure that a brand new analyst to achieve success when employed, they want a transparent roadmap as to what knowledge is obtainable within the Knowledge Warehouse, the place it’s sourced, and what its enterprise context is. Nonetheless, groups with poorly modeled knowledge usually wrestle to onboard new candidates, not understanding why it’s taking new hires so lengthy to reply primary enterprise questions. With out the correct mentorship, analytics groups can expertise excessive churn charges as a result of new members usually are not given the instruments they should succeed.

Knowledge Analysts and Knowledge Scientists must be targeted on answering enterprise issues and never losing time to search out the place enterprise entities stay. The sooner groups can develop into conversant in what knowledge is obtainable, the faster that dashboards and predictive fashions might be accomplished. This finally boosts the staff’s productiveness.

If there are solely a handful of analysts who know the right way to reply primary enterprise questions, that could be a drawback. Working in such a siloed strategy is not scalable and can solely restrict the variety of issues that the staff is ready to clear up.

Photo by Desola Lanre-Ologun on Unsplash

2.) Totally different Analysts are Producing Totally different Outcomes For The Similar Metrics

If there isn’t a single supply of fact, it may be straightforward for various staff members to calculate the identical metric in several methods. For instance, how is Income outlined? And what tables are used to calculate this? There must be a transparent path to outline enterprise logic, which all begins with an intentional knowledge mannequin.

I’ve labored in environments the place there have been 3 totally different tables which have represented the identical enterprise entity, which all utilized totally different SQL logic to reach at an analogous, however not the identical report output. Couple this situation with a poorly managed reporting request queue, and you’ve got two totally different analysts answering the identical query with totally different outcomes. This not solely causes stakeholders to lose belief within the knowledge, but in addition requires tedious and unneeded reconciling work throughout groups.

3.) Groups Have to Reuse Redundant Code Blocks for Enterprise Logic

I’ve seen groups have a google sheet of SQL CASE statements which define particular enterprise metrics. These have been lengthy in nature & tough to learn by means of. Whereas it makes an attempt to supply consistency throughout groups, the issue with that is that it violates DRY (Do not Repeat Your self) ideas throughout the group.

For a lot of groups with this kind of difficulty, utilizing a metamorphosis instrument similar to DBT permits Analytics Engineers to outline enterprise logic in a single place after which have analysts reference it in lots of locations.

Take into consideration the next instance— when you’re an ecommerce firm and there’s a complicated method to calculate web page views (which is okay), why would you be distributing & duplicating that enterprise logic to occur in your BI instrument? Not solely is that this dangerous in case logic is not copied and pasted in the very same approach each time, however it’s a waste of compute, which is the biggest expense from most cloud suppliers.

To resolve for this, think about mapping out frequent aggregations and enterprise logic that should happen, run a metamorphosis job each day (or as continuously as wanted) and write it to a desk. Then have your BI layer sit on high of that.

4.) Your Knowledge Warehouse Performs Poorly

As identified above, poorly modeled knowledge introduces redundancy. However it additionally creates pointless complexity. Extra computing sources is a biproduct of this, and all cloud knowledge warehouses have limits as much as a sure pricing threshold. As soon as that restrict is reached, executing new queries might develop into extraordinarily gradual and never even possible in some circumstances.

Any Knowledge Engineer will let you know that simply buying extra sources just isn’t a sustainable answer to this drawback.

Lengthy and complicated queries not solely take lengthy to execute on their very own, however will diminish the out there sources in your atmosphere. Contemplate an instance the place it is advisable to run a question that includes 20 joins. There are only a few situations the place this is a perfect answer, because it illustrates that the information wanted to reply a enterprise drawback just isn’t saved in a format that’s simply accessible. This many joins might be computationally costly, particularly when the associated tables are massive in quantity or if the ON clause includes a number of columns. If you’re implementing a dimensional mannequin, your staff may need to think about creating a brand new reality desk in your database in these situations.

Assets are measured in several methods relying on what cloud supplier you’re utilizing, however all of them observe the identical idea of utilizing a devoted variety of digital CPUs. For instance, BigQuery makes use of the idea of slots, which successfully is the variety of out there computing sources used to execute a question. Organizations with on demand pricing obtain 2,000 slots for use at any given cut-off date. So, if one question is extremely complicated & takes up greater than the out there variety of slots, different queries will sit within the queue earlier than they will even be executed.

5.) You Usually Must Arduous Code Values in SQL

Arduous coded values are sometimes a tell-tale signal that there’s required knowledge lacking in your Knowledge Warehouse. Within the context of a dimensional mannequin, this often signifies that a brand new dimension desk must be created to supply extra columns.

Zach Quinn wrote an article which outlines this idea very well, demonstrating the right way to remove lengthy CASE statements with a lookup desk. Placing this instance within the context of a dimensional mannequin — suppose your group must do a whole lot of geospatial evaluation. You might have a customer_dimension desk that provides the state abbreviation, however you need to show it as a full state title. You could possibly write one thing like this:

, customer_name
, deal with
, metropolis
, state AS state_abrevaition
WHEN state = 'NJ' THEN 'New Jersey'
WHEN state = 'NY' THEN 'New York'
WHEN state = 'PA' THEN 'Pennsylvania'
END AS state_full_name
, zip_code
FROM customer_dimension

However this kind of CASE assertion is not sustainable. If we need to enhance upon this answer in better element, we have to be part of a zip_code_dimension desk to the customer_dimension desk. You’ll see beneath {that a} zip_code_dimension will give us even better granularity in an evaluation. The desk may look one thing like this:

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