What a cloud data source does
Cloud data sources let Tealium read directly from a warehouse - Snowflake, BigQuery, and similar platforms - rather than waiting for the warehouse to push a file or fire a webhook. It is the inbound path for enrichment attributes that already live correctly somewhere else: lifetime value, churn score, loyalty tier, and similar computed fields.
When it beats the alternatives
Any time a valuable attribute already exists in the warehouse, and re-deriving the same logic client-side or in a File Import feed would duplicate work and eventually drift from the source of truth. If the data science or BI team owns the calculation, the cloud data source is usually the more honest integration point than reimplementing their logic inside Tealium.
How to implement it properly
Connect the warehouse with credentials scoped to a read-only role and a narrow schema - this is self-evident and still frequently skipped. Define the exact query or table the source reads, rather than pointing it at an entire schema and hoping the mapping sorts itself out. Set a sync cadence that matches how often the underlying warehouse table actually refreshes; syncing hourly against a table that updates nightly does not create fresher data, only more sync jobs. Map returned columns to visitor attributes explicitly.
How to verify it worked
Confirm the cadence actually ran by checking the source's sync log and timestamp, not just that the source is enabled. Then confirm the attribute value on a known test profile matches the corresponding row in the warehouse directly - a sync that "succeeded" but mapped a stale or wrong column will report healthy indefinitely.
Security note stated plainly: warehouse credentials for a cloud data source should never be broader than they need to be. A read-only, narrowly-scoped service account is not extra caution - it is the baseline.