Named senior engineers on call for WAL, replication, and failover events
PostgreSQLDebeziumKafka
PrometheusWAL volume incidents stopped entirely. Consumer stalls now surface as pipeline lag alerts hours before they could affect the primary, and the customer's team handles routine cases without escalating.
Overview
A banking platform used logical decoding to feed a change data capture pipeline. When the downstream consumer stalled, the replication slot stopped advancing and the primary retained every WAL segment since the stall. Disk filled twice before AceMQ took over support with named senior engineers and direct escalation, no tier-1 triage.
Challenge
A retained replication slot is one of the few conditions that can take a PostgreSQL primary down through a mechanism unrelated to query load. The customer's monitoring watched disk usage but not slot lag, so the first signal was a disk alert with minutes of headroom left. Distinguishing a temporarily slow consumer from a genuinely abandoned slot required judgment the on-call rotation did not have.
Environment
PostgreSQL on AWS with logical replication feeding a Debezium and Kafka change data capture pipeline.
Approach
AceMQ instrumented slot lag as a first-class signal ahead of disk usage, then established policy for slot lifecycle: what triggers investigation, what triggers a consumer restart, and what justifies dropping a slot. Guardrails were configured so a stalled consumer degrades the pipeline instead of the primary.
Solution
- 1Added replication slot lag and WAL retention size to monitoring with thresholds well ahead of disk exhaustion
- 2Configured max_slot_wal_keep_size so a stalled consumer invalidates its slot rather than filling the WAL volume
- 3Separated WAL onto its own volume with independent capacity and alerting
- 4Documented slot lifecycle policy covering investigation, consumer restart, and safe slot removal
- 5Reviewed checkpoint and WAL sizing settings that were driving unnecessary write amplification
- 6Established 24/7 escalation directly to senior PostgreSQL engineers for slot and replication incidents
Outcome
WAL volume incidents stopped entirely. Consumer stalls now surface as pipeline lag alerts hours before they could affect the primary, and the customer's team handles routine cases without escalating.
Technologies
PostgreSQLDebeziumKafkaPrometheusRelated Use Cases
PostgreSQL Autovacuum and Transaction ID Wraparound Remediation
Emergency intervention on a database approaching transaction ID wraparound because autovacuum could not keep pace with the largest tables.
PostgreSQL High Availability and Failover Design
Designing an automated failover architecture with quorum-based leader election, synchronous replication policy, and tested recovery procedures.
Need Expert PostgreSQL Support?
AceMQ's senior PostgreSQL engineers have handled this exact type of engagement before. Whether you need architectural guidance, hands-on remediation, or an ongoing managed partnership, we're ready to help.