> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vortexiq.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Active Streaming Replicas, PostgreSQL

> Active Streaming Replicas for PostgreSQL instances. Tracked live in Vortex IQ Nerve Centre. How to read it, why it matters, and how to act on it.

**Card class:** [Non-Hero](/nerve-centre/overview#card-classes-explained)  •  **Category:** [Replication](/nerve-centre/connectors#connectors-by-type)

## At a glance

> The count of physical streaming standbys currently connected to the primary and actively receiving WAL. This is the headcount of your high-availability and read-scaling fleet: it answers "how many standbys are attached right now?" If the number you designed for is two and the card reads one, a standby has dropped out and your redundancy has quietly halved, often long before anyone notices the missing capacity.

## What it tracks

The card reports Active Streaming Replicas for the selected period, refreshed in real time (`RT`). It counts the rows in `pg_stat_replication` on the primary whose `state` is a live streaming value (`streaming`, `catchup`, or `backup`), one row per connected standby. A standby that has disconnected drops out of the view and the count falls. Read this number against your intended topology: a stable count that matches your design is healthy; a drop is the signal that a replica has fallen off, which removes both a read-scaling node and a failover candidate. Because the count says nothing about freshness, always pair it with [Replication Lag (seconds)](/nerve-centre/kpi-cards/postgresql/replication-lag-seconds) and [WAL Lag Bytes (primary to standby)](/nerve-centre/kpi-cards/postgresql/wal-lag-bytes-primary-standby): a standby can be connected (counted here) yet badly behind. [Failover Readiness](/nerve-centre/kpi-cards/postgresql/failover-readiness) then tells you whether any of the counted standbys is actually safe to promote. On managed services the count is reconciled with the provider's read-replica inventory (RDS read replicas, Aurora reader instances, Cloud SQL replicas).

## Reconciling against the source

Confirm the count natively with `SELECT count(*) FROM pg_stat_replication;` on the primary, or list the standbys with `SELECT application_name, state, sync_state FROM pg_stat_replication;`. On managed services compare against the provider's own inventory: the read-replica list in the RDS console, Aurora reader instances in the cluster, or the replica list in Cloud SQL. A native count higher than the card usually means a standby is connected but in a non-streaming state; a count lower means a replica has disconnected since the last refresh.

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### Tracked live in Vortex IQ Nerve Centre

*Active Streaming Replicas* is one of hundreds of KPI pulses Vortex IQ tracks across PostgreSQL and 70+ other ecommerce connectors. Nerve Centre runs the detection layer; Vortex Mind investigates the cause when something moves; Ask Viq lets you interrogate any number in plain English.

[Start for free](https://app.vortexiq.ai/login) or [book a demo](https://www.vortexiq.ai/contact-us) to see this metric running on your own data.