RabbitMQ Management UI shows "?" or no statistics for Stream storage

Products

• VMware Tanzu RabbitMQ

Issue/Introduction

When viewing RabbitMQ Streams in the Management UI, the "Memory" or storage-related columns display a question mark (?) or show as 0, even when the stream is actively receiving and storing messages. Users may expect to see memory utilization metrics similar to those provided for Classic or Quorum queues.

Environment

• Product: VMware Tanzu RabbitMQ
• Feature: RabbitMQ Streams
• Plugin: RabbitMQ Management Plugin

Cause

This behavior is by design and reflects the architectural difference between Streams and traditional queue types:

1. Classic and Quorum Queues: these types back messages using Erlang processes. They track message indices, delivery states, and metadata directly within the Erlang process heap memory. The Management UI calculates the "Memory" column value by querying these active Erlang process allocations.
2. RabbitMQ Streams: Streams are architected as high-performance, append-only disk logs. Message payloads bypass traditional Erlang queue process memory allocations and are flushed sequentially straight to segment files on disk.

Resolution

The lack of statistics in the "Memory" column for Streams does not indicate a system error or missing data.