ai-automation-consultant / Failure Lab

Database Unique Constraint

Parallel sync workers collide while creating the same company row.

Failure LabDashboard

Category

database

Difficulty

standard

Last Run

none

Incident Brief

Diagnose the database error and describe a concurrency-safe fix.

Broken State

Two workers insert the same normalized domain instead of using an upsert.

Symptoms

  • The error appears only under parallel load.
  • The unique index is on normalized company domain.

Trace

db.error=P2002 unique constraint failed on Company_domain_key
company.domain=example.com worker=sync-2

Diagnosis