Data Products - Part II: The Complexity Challenge
Creating data products within a data mesh resumes in “partitioning” a given set of inputs, outputs and transformations to create something that looks like a Lego structure, in which each Lego piece represents a data product. The word partition is improperly used as there can be overlapping in terms of inputs, outputs and transformations, though in an ideal solution the outcome should be close to a partition.
If the complexity of inputs and outputs can be neglected, even if their number could amount to a big number, not the same can be said about the transformations that must be performed in the process. Moreover, the transformations involve reengineering the logic built in the source systems, which is not a trivial task and must involve adequate testing. The transformations are a must and there’s no way to avoid them.
When designing a data warehouse or data mart one of the goals is to keep the redundancy of the transformations and of the intermediary results to a minimum to minimize the unnecessary duplication of code and data. Code duplication becomes usually an issue when the logic needs to be changed, and in business contexts that can happen often enough to create other challenges. Data duplication becomes an issue when they are not in synch, fact derived from code not synchronized or with different refresh rates.
Building the transformations as SQL-based database objects has its advantages. There were many attempts for providing non-SQL operators for the same (in SSIS, Power Query) though the solutions built based on them are difficult to troubleshoot and maintain, the overall complexity increasing with the volume of transformations that must be performed. In data mashes, the complexity increases also with the number of data products involved, especially when there are multiple stakeholders and different goals involved (see the challenges for developing data marts supposed to be domain-specific).
To growing complexity organizations answer with complexity. On one side the teams of developers, business users and other members of the governance teams who together with the solution create an ecosystem. On the other side, the inherent coordination and organization meetings, managing proposals, the negotiation of scope for data products, their design, testing, etc. The more complex the whole ecosystem becomes, the higher the chances for systemic errors to occur and multiply, respectively to create unwanted behavior of the parties involved. Ecosystems are challenging to monitor and manage.
The more complex the architecture, the higher the chances for failure. Even if some organizations might succeed, it doesn’t mean that such an endeavor is for everybody — a certain maturity in building data architectures, data-based artefacts and managing projects must exist in the organization. Many organizations fail in addressing basic analytical requirements, why would one think that they are capable of handling an increased complexity? Even if one breaks the complexity of a data warehouse to more manageable units, the complexity is just moved at other levels that are more difficult to manage in ensemble.
Being able to audit and test each data product individually has its advantages, though when a data product becomes part of an aggregate it can be easily get lost in the bigger picture. Thus, is needed a global observability framework that allows to monitor the performance and health of each data product in aggregate. Besides that, there are needed event brokers and other mechanisms to handle failure, availability, security, etc.
Data products make sense in certain scenarios, especially when the complexity of architectures is manageable, though attempting to redesign everything from their perspective is like having a hammer in one’s hand and treating everything like a nail.
Originally published at https://sql-troubles.blogspot.com.
