System Design

Reliable Cache Invalidation with Change Data Capture

System Design diagram · made in Skemio

Architecture diagram showing CDC pipeline: application writes to PostgreSQL WAL, Debezium streams events to Kafka, and workers invalidate Redis.
Architecture diagram showing CDC pipeline: application writes to PostgreSQL WAL, Debezium streams events to Kafka, and workers invalidate Redis.
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What it shows

  • Database WAL is the single source of truth; prevents dual-write anomalies.
  • Debezium tails row mutations asynchronously without adding write latency.
  • Eviction consumers read Kafka change events to purge stale Redis keys.

The takeaway

Tail database transaction logs to guarantee cache eviction without dual-write complexity.

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