Database Concurrency — Sequence Migration & Race Condition Fix
Migrated legacy multi-app MAX() ID generation to atomic database sequences, eliminating critical race conditions.
Duplicate key errors completely eliminated.
Coordinated across all shared database consumers.
Native database sequence generation.
Three separate enterprise applications sharing a single database generated IDs using MAX(id) + 1, causing concurrent race conditions and duplicate key collisions.
Eliminated race conditions across all 3 applications by migrating legacy ID generators to database sequences, ensuring atomic sequence increments and absolute data integrity.
Project description
Diagnosed intermittent duplicate key violations and data integrity anomalies caused by MAX(id) + 1 generation across 3 applications sharing a common database.
Architected and executed a migration to database sequences, replacing application-level computations with database-native sequence increments.
Coordinated rollout across all 3 participating services to synchronize sequence counters with zero downtime.
Guaranteed atomic ID allocation and absolute concurrency safety under concurrent write loads.
Why I built this
Three separate enterprise applications writing concurrently to shared tables generated identical IDs during high-traffic overlap.
Resolved data integrity threats and eliminated failed insert transactions.
Process and execution
How the work moved
- Identified intermittent duplicate key errors and data inconsistency caused by non-atomic MAX() ID queries during concurrent writes.
- Proposed and demonstrated database sequences as the ideal architectural solution across shared multi-application databases.
- Migrated shared table primary key generation logic to database sequences across all 3 participating applications.
- Verified zero concurrency collisions under simultaneous load testing.
What I owned
- Led the work as Associate Consultant - Java Backend Developer.
- Turned messy context into a clearer operating model, interaction direction, and rollout shape.
- Worked across stakeholders to move the project from framing into execution.
Notable decisions
Database sequence adoption
Replaced application-level MAX(id) calculations with database-level sequences to guarantee atomic, collision-free ID generation.
Coordinated 3-app rollout
Synced sequence starting values and deployed updates simultaneously across 3 interconnected application services.
What I learned from this
Application-level MAX() ID generation is inherently unsafe in multi-client or multi-application architectures.
Database sequences provide atomic, lock-free ID generation with guaranteed consistency.