postgres-replication-stats
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.
Compatible sources:
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.
Example
tools:
replication_stats:
kind: 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. |