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Event Sourcing over CRUD for Audit Trails
Moved financial transaction audit trail from CRUD to Event Sourcing using Kafka for immutable event logging, with Postgres materialized views for reads, to satisfy compliance requirements.
lesson_learnedevent-sourcingaudit-trailcompliancekafkapostgresarchitecture
Created 7/27/2026, 7:53:20 AM
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The team decided to move from standard CRUD in PostgreSQL to Event Sourcing for the financial transaction audit trail. The current CRUD approach loses history because updates overwrite previous states. Compliance could not trace who changed transaction #8821 from pending to approved. Database triggers were considered but rejected because they lose business context. The chosen approach uses Kafka as the immutable event log and builds materialized views in Postgres for fast frontend reads. Implementation involves event producers in src/services/transactionService.ts and consumer/store logic in src/events/eventStore.ts. Reference: Martin Fowler Event Sourcing Pattern.