feat: publish CDC stream via logical replication - #592
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thlpkee20-wq merged 3 commits intoJul 29, 2026
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Add CDC consumer, pgoutput decoder, and pluggable sink interface (Kafka, stdout, in-memory) for streaming row-level changes from PostgreSQL logical replication to downstream consumers. - Add migration 0014 to create "stellabill_cdc" publication with column allowlists that exclude PII columns (PII-safe by design) - Implement pgoutput binary protocol decoder supporting INSERT, UPDATE, DELETE, BEGIN, COMMIT, RELATION, ORIGIN, and TYPE messages - Implement Consumer with reconnection loop, standby status updates, and graceful shutdown via context cancellation - Implement pluggable Sink interface with MemorySink (testing), KafkaSink (production), and StdoutSink (debugging) - LSN advancement gated on successful sink writes to prevent data loss - Build helper functions for crafting pgoutput binary messages in tests - 77.5% test coverage with 60+ test cases covering decoder edge cases, consumer lifecycle, reconnect logic, and sink implementations closes Stellabill#417
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Summary
Adds a Change Data Capture consumer that streams row-level changes from PostgreSQL logical replication to pluggable sinks (Kafka, stdout, in-memory), enabling downstream analytics and search indexers without polling.
closes #417
Changes
Migration (
migrations/0014_create_cdc_publication)stellabill_cdcpublication using pgoutput pluginsubscriptions.customer,statements.customer_idoutbox_events.event_data,outbox_attempts.response_body,contract_events.payloadidempotency_keys.response_body,subscriber_keys.jwkexport_operations.caller_id,notification_preferences.*,saga_instances.contextoutbox_attempts.error_message,saga_step_results.error_messageCDC Package (
internal/cdc/)consumer.gopgoutput.gosink.goSinkinterface +MemorySinkfor testing +ConsumerConfigkafka_sink.goMessageWriterinterface abstractionstdout_sink.goKey Design Decisions
Sinkinterface allows adding any downstream (S3, BigQuery, Elasticsearch, etc.)MessageWriterinterface decouples from specific Kafka clientTest Coverage
runReplication(5.8%),execSimple(0%),sendStandbyStatusUpdate(0%) require real PG withwal_level=logicalfor full coverage-raceenabledSecurity