What is a single source of truth?
The test is simple. When marketing, finance, and operations ask the same question, they get the same number.
The phrase is often misunderstood as "put all the data in one place." Centralizing storage helps, but it isn't the hard part. Two teams can query the same warehouse and still disagree, because they calculated the metric differently. A true source of truth governs the definitions, not just the data.
What does a single source of truth need?
| Ingredient | What it means | What breaks without it |
|---|---|---|
| Connected data | Every relevant source flows into one governed foundation | Teams pull their own exports and work from different snapshots |
| Shared definitions | Each KPI is defined once | ROAS means one thing to marketing and another to finance |
| Harmonized naming | Platform and market labels map to one taxonomy | One campaign shows up as five |
| Governance | Changes are deliberate, tracked, and owned | Definitions drift quietly |
| Lineage | Every number traces back to its source | Nobody can explain why numbers differ |
What is an example of a single source of truth?
One revenue number in the board meeting
Marketing reports revenue from platform conversions. Finance reports revenue from the order system, net of returns. Both decks reach the board with different numbers, and the meeting stalls.
With a single source of truth, revenue is defined once, from agreed sources and rules, and every deck, dashboard, and AI answer uses that definition. The conversation moves from "whose number is right" to "what do we do next."
Single source of truth vs. a single database
| A single database | A single source of truth | |
|---|---|---|
| What is centralized | Storage | Data, definitions, and rules |
| Can teams still disagree? | Yes, if they calculate differently | Not on the math, because the logic is shared |
| Who it serves | Mainly technical teams | Every team and tool, including AI |
| What keeps it trustworthy | Data quality checks | Governance, lineage, and version control |
Why does a single source of truth matter?
Without one, every meeting starts with reconciliation. Leaders lose confidence in the numbers, decisions get delayed, and AI tools give answers that disagree with the dashboards.
- Faster decisions. Meetings move straight to what to do next.
- Aligned teams. Marketing, finance, and operations work from the same definitions.
- Less rework. Analysts stop rebuilding the same logic in every report.
- Consistent AI answers. AI tools answer from the same definitions people use.
How does Alli do this?
In Alli by PMG, Alli Semantic Layer is where business logic is defined once. It sets shared KPI definitions, models how data connects to campaigns, accounts, and calendars, and uses Categorizations to map platform naming into one taxonomy, consistently across regions and currencies.
Every dashboard, Data Explorer view, Ask Alli answer, alert, and planning tool reads from those same definitions, so teams, regions, and tools work from the same numbers. Change a definition once, and it applies everywhere.
Explore Alli Semantic LayerSingle source of truth FAQ
What does single source of truth mean?
It means one agreed, governed version of data and definitions that everyone uses. Ask the same question in a dashboard, a finance deck, or an AI tool, and you get the same answer.
Is a data warehouse a single source of truth?
Not on its own. A warehouse centralizes storage, but teams can still calculate metrics differently on top of it. Shared, governed definitions are what make the answers consistent.
Why do single source of truth projects fail?
Usually because metric logic keeps getting rebuilt in individual spreadsheets, dashboards, and tools, and naming varies by platform and market. Without shared definitions and governance, the numbers drift apart again.
How does a semantic layer create a single source of truth?
It defines each metric, entity, and mapping once, between the data and the tools that use it, so every report and AI tool reads the same logic.
Last updated ‹ Back to the glossary