Postgres Get Replication Slots: Online Management Guide 2026

Efficiently manage PostgreSQL replication slots online in 2026 with this step-by-step guide. Replication slots ensure no WAL data loss during streaming replication, vital for high-availability clusters.

Query active slots, drop inactive ones, and monitor usage to prevent disk bloat. Updated for Postgres 17 features like advanced slot stats.

Step 1: Query Replication Slots

Connect via psql and run: SELECT * FROM pg_replication_slots;. This lists slot_name, plugin, slot_type, database, active, and wal_status.

  • Identify inactive slots
  • Check restart_lsn
  • Note xmin horizon

Step 2: Check Online Slot Status

For real-time: SELECT slot_name, active, wal_status FROM pg_replication_slots WHERE active = false;. Use pg_stat_replication for subscriber view.

  • Monitor via pgAdmin
  • Set up alerts on inactive
  • Combine with pg_stat_wal_receiver

Step 3: Drop Unused Slots Safely

Ensure no subscribers, then: SELECT pg_drop_replication_slot('slot_name');. For logical slots, confirm no transactions blocked.

  • Backup first
  • Advance xmin if needed
  • Use pg_terminate_backend

Step 4: Create New Slots Dynamically

Online creation: SELECT pg_create_physical_replication_slot('slot1'); or logical with pg_create_logical_replication_slot('slot2', 'pgoutput');

  • Specify two_phase for logical
  • Use reserve_wal
  • Test with pg_recvlogical

Step 5: Monitor and Automate

Script cron jobs: Vacuum slots older than 7 days. Use extensions like pg_repack or check_postgres.pl for dashboards in 2026 clouds.

  • Grafana integration
  • CloudWatch for AWS RDS
  • Patroni for auto-healing

Best Practices 2026

Limit max_slots_per_database. Use temporary slots for one-offs. Monitor WAL accumulation with pg_ls_waldir.

  • Set replication_slots_active_check
  • Logical decoding caveats
  • Scale for multi-standby

Frequently Asked Questions

What is a Postgres replication slot?

A slot reserves WAL for replicas, preventing premature purge even if subscribers lag.

How to list online replication slots?

SELECT * FROM pg_replication_slots; run anytime without downtime.

Why drop inactive slots?

They hold WAL files, risking disk full. Regular cleanup essential.

Difference physical vs logical?

Physical for binary copy, logical for SQL changes via output plugins.

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