Orientation
What You'll Master Here
Ask three systems "who is customer Mara?" and you get three different answers: the CRM has "Mara O’Neil," billing has "M. ONeil," support has "mara oneil," each with its own id. Master Data Management (MDM) is the discipline of turning that scattered mess into one trusted, authoritative record per real-world entity.
You will learn what master data is (and how it differs from transactional and reference data), the identity-resolution pipeline that decides which records are the same entity, how match thresholds balance false merges against missed ones, survivorship rules that assemble the golden record field by field, and the MDM styles and governance that keep it trustworthy.
This is shown with real matching logic and survivorship examples, because MDM lives or dies on getting "is this the same person?" right, merge too eagerly and you fuse two real customers; merge too timidly and you keep paying for duplicates.
Why it matters
Almost every cross-system analysis (customer lifetime value, total exposure, a single customer view) is wrong if the same entity appears as several records. MDM is what makes "one customer = one row" true across the enterprise.
Core mental model
Many source records for one real entity → resolve which are the same → merge by survivorship rules → one golden record, with lineage back to its sources.
- master data
- Core business entities shared across systems: customers, products, suppliers, accounts.
- golden record
- The single, trusted, merged representation of one real-world entity.
- identity resolution
- Deciding which source records refer to the same real entity (also entity resolution).
- survivorship
- The rules that pick the winning value for each field of the golden record.
Common mistake
Assuming each source’s customer id is the real, shared identity.
The same person counts as several customers; every cross-system metric is inflated and contradictory.
Better habit
- Treat shared core entities as master data needing one golden record.
- Resolve identity before computing cross-system metrics.
- Keep lineage from each golden record back to its sources.
MDM answers "who/what is this, really?" across systems. It is the cross-system cousin of the keys-and-identity chapter: identity, but when no shared key exists.
Follow customer Mara through the pipeline: messy across three systems → matched → merged into one golden record with field-level provenance.
Practice prompts
- Name three master-data entities in a business you know.
- Describe a metric that breaks when one customer appears as three records.
Remember this
MDM produces one trusted golden record per real-world entity from many conflicting sources, via identity resolution and survivorship, so "one customer" means one record everywhere.