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Data platform · Quality & Contracts

Data quality tests

Easyplatform-13
data qualitytestsuniquenot_null

Question

What kinds of data quality tests should a platform run?

Solution

Data quality tests check whether tables meet expectations before people trust them.

Common categories

  • Completeness: not null on required fields; row count > 0
  • Uniqueness: primary key / grain key unique
  • Validity: values in allowed sets; ranges make sense
  • Consistency: relationships between tables (FK-like)
  • Accuracy: reconciliations vs source totals (harder, high value)
-- uniqueness idea
select order_id, count(*)
from fct_orders
group by 1
having count(*) > 1;

Tools: dbt tests, Great Expectations, custom SQL monitors.

Interview tip: Give 3-4 categories with one concrete check each. Mention blocking vs warning severities for production.

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