googleapis--mcp-toolbox/docs/en/integrations/postgres/tools/postgres-replication-stats.md

title, type, weight, description

title	type	weight	description
postgres-replication-stats	docs	1	The "postgres-replication-stats" tool reports replication-related metrics for WAL streaming replicas, including lag sizes presented in human-readable form.

About

The postgres-replication-stats tool queries pg_stat_replication to surface the status of connected replicas. It reports application_name, client address, connection and sync state, and human-readable lag sizes (sent, write, flush, replay, and total) computed using WAL LSN differences.

This tool takes no parameters. It returns a JSON array; each element represents a replication connection on the primary and includes lag metrics formatted by pg_size_pretty.

Compatible Sources

{{< compatible-sources others="integrations/alloydb, integrations/cloud-sql-pg">}}

Example

kind: tool
name: replication_stats
type: postgres-replication-stats
source: postgres-source
description: "Lists replication connections and readable WAL lag metrics."

Example response element:

{
  "pid": 12345,
  "usename": "replication_user",
  "application_name": "replica-1",
  "backend_xmin": "0/0",
  "client_addr": "10.0.0.7",
  "state": "streaming",
  "sync_state": "sync",
  "sent_lag": "1234 kB",
  "write_lag": "12 kB",
  "flush_lag": "0 bytes",
  "replay_lag": "0 bytes",
  "total_lag": "1234 kB"
}

Reference

field	type	required	description
pid	integer	true	Process ID of the replication backend on the primary.
usename	string	true	Name of the user performing the replication connection.
application_name	string	true	Name of the application (replica) connecting to the primary.
backend_xmin	string	false	Standby's xmin horizon reported by hot_standby_feedback (may be null).
client_addr	string	false	Client IP address of the replica (may be null).
state	string	true	Connection state (e.g., streaming).
sync_state	string	true	Sync state (e.g., async, sync, potential).
sent_lag	string	true	Human-readable size difference between current WAL LSN and sent_lsn.
write_lag	string	true	Human-readable write lag between sent_lsn and write_lsn.
flush_lag	string	true	Human-readable flush lag between write_lsn and flush_lsn.
replay_lag	string	true	Human-readable replay lag between flush_lsn and replay_lsn.
total_lag	string	true	Human-readable total lag between current WAL LSN and replay_lsn.