Master Data Holder

_{Published: 06 July 2025}

Known Uses

The Master Data Holder pattern is frequently used in APIs within both the Dutch government and the Dutch energy sector domains. These sectors often expose long-lived, high-quality reference data, such as registers, addresses, and energy connection points – through dedicated API endpoints, following the principles of the Master Data Holder pattern to ensure data consistency and accessibility across organizations. Examples:

• KVK Handelsregister suite (Chamber of Commerce Business Register Suite). Several KVK APIs serve as authoritative company master-data holders:
  • KVK Handelsregister Basisprofiel API: with GET /basisprofielen/{kvkNummer} to retrieve basic information for a specific company
  • KVK Handelsregister Naamgeving API: with GET /naamgevingen/kvknummer/{kvkNummer} to request naming information for a specific company based on a Chamber of Commerce number
  • KVK Handelsregister Vestigingsprofiel API: with GET /vestigingsprofielen/{vestigingsnummer} to request information for a specific business location

These endpoints provide the canonical company information (legal name, RSIN, addresses, ownership, activity codes) which:

• Changes infrequently (company details seldom change day-to-day)
• Is consumed by many downstream services (credit checks, regulatory reporting, public directories)
• Exposes all retrieval operations needed for consumers of master data
• The OData API of the Dutch House of Representatives (Tweede Kamer) – exemplifies the Master Data Holder pattern by offering consistent, authoritative access to core parliamentary data such as members and party information. The API is read-only, with no public write or delete operations, reflecting standard practice for open government data. It serves as a reliable source for external systems, researchers, and the public, supporting transparency and trust in official information.
• EDSN (Energy Data Services Netherlands) plays a vital role in the Dutch energy sector by maintaining official registers that serve as trusted sources of master data. These registers – examples of the Master Data Holder pattern – are made available to key market participants, including suppliers, grid operators, and metering companies, through Community APIs. This shared access helps support their daily operations and ensures reliable, high-quality data exchange across the entire energy sector. To mention a few registers:
  • CAR: Central Connections Register – central register with data of all electricity and gas connections in the Netherlands
  • CERES: The is the central registration system for energy-producing and energy-consuming installations
  • CPR: The register of market participants’ contact persons

Discussion Input

The book covers several design implications of the Master Data Holder Pattern, and we found them really insightful. Here’s our take on it:

• One-way references: Master data gets referenced by operational data, but not the other way around. This helps avoid circular dependencies and keeps things clean.
• Delete handling: Instead of actually deleting records, they’re often just marked as inactive – for compliance, audit trails, and to avoid accidental data loss.
• When to use It: This pattern works well when the data is stable, heavily used by other parts of the system, and needs to be accurate and well-protected.
• Change impact: Be extra careful with updates and deletions since master data is widely referenced, changes can have a big ripple effect.
• Data quality and protection: Master data needs strong validation, access control, and audit logs. It is the kind of data you really want to get right.
• Centralized Management: Master Data Holders often act as the go-to source of truth. That’s great for consistency and governance, but you’ll need to think about how to scale and keep them available.
• Extensibility: The pattern also leaves room for things like bulk updates, archiving, or time-based queries depending on your domain’s needs.