Postgres Get Replication Slots: Complete Guide 2026

Master postgres get replication slots commands in PostgreSQL 17 (2026 standard). Essential for logical replication monitoring and high availability setups.

Use SQL queries to list, check lag, and drop slots preventing WAL bloat.

Basic Query: List All Slots

Core command.

  • SELECT * FROM pg_replication_slots;
  • Shows slot_name, plugin, slot_type
  • Check active vs inactive

Check Replication Lag

Monitor health.

  • SELECT slot_name, (now() - restart_lsn) as lag;
  • WAL bytes behind primary
  • Alert on >1GB

Drop Unused Slots

Prevent bloat.

  • SELECT pg_drop_replication_slot('slotname');
  • Force drop inactive
  • Vacuum after cleanup

Advanced Monitoring Queries

Production scripts.

  • JOIN pg_stat_replication
  • Lag in time units
  • Export to Prometheus

Logical vs Physical Slots

Differences.

  • pgoutput plugin logical
  • Physical for streaming
  • Max 100 slots default

2026 Best Practices

PG 17 updates.

  • Auto-drop config
  • Reserve WAL space
  • Patroni integration

Troubleshooting Common Issues

Fix WAL buildup.

  • Increase max_slot_wal_keep_size
  • Restart subscriber
  • Archive WAL logs

Frequently Asked Questions

How to get replication slots in Postgres?

SELECT * FROM pg_replication_slots; lists all with details like active status and WAL position.

What causes replication slot WAL bloat?

Inactive subscribers hold WAL files. Monitor with pg_replication_slots and drop unused slots promptly.

Can I script slot monitoring?

Yes, use cron jobs with psql queries exporting to Grafana for alerts on lag >5min.

Max replication slots in PG17?

Default 100, configurable via max_replication_slots. Physical slots consume more resources.

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