The Replication Slot Retained WAL alert notifies you when its configured condition is met on PostgreSQL instances so you can investigate and respond.
Mini DBA describes this alert as: Replication slots retaining too much WAL can fill the WAL volume when consumers lag or disappear. Mini DBA evaluates this alert once a minute so changes are detected quickly.
This alert shows that replication slots are retaining enough WAL to threaten disk capacity, usually because a consumer is lagging, disconnected, or no longer exists.
Enable it where replication, read replicas, failover, or reporting copies are part of the service design. Disable it on standalone systems that do not use replication so the alert list stays focused.
Threshold meaning: GB retained. Major threshold: 50 GB. Minor threshold: 10 GB. Comparison direction: over. For an over-threshold alert, decreasing a threshold makes that severity fire sooner; increasing it tolerates more load or pressure. Set the minor threshold as an early-warning level and the major threshold at the highest acceptable value for the service.
Identify the slot and consumer, restore the consumer or advance or drop an obsolete slot through an approved PostgreSQL procedure, and add temporary disk capacity if needed. Never delete files manually from pg_wal; doing so can make the server unrecoverable.
Keep this alert enabled because retained WAL can grow until the volume fills. Set thresholds from available disk headroom and the time needed to repair a consumer or approve slot removal.