Merge pull request #4454 from rabbitmq/mergify/bp/v3.10.x/pr-4452v3.10.0-rc.3v3.10.0-rc.2

Update 3.10.0 release notes (backport #4452)

1 files changed, 28 insertions, 0 deletions

diff --git a/release-notes/3.10.0.md b/release-notes/3.10.0.md
index 2754631f87..dba6213f21 100644
--- a/release-notes/3.10.0.md
+++ b/release-notes/3.10.0.md
@@ -158,6 +158,13 @@ Release notes are kept under [rabbitmq-server/release-notes](https://github.com/
 
 #### Internal API and Other Changes
  
+ * Two rarely used classic queue metrics have been removed. Their removal reduces pressure
+   on internal table writes and boosts classic queue v1 throughput by 10 to 20 percent.
+
+   Contributed by @felixhuettner.
+
+   GitHub issue: [#4431](https://github.com/rabbitmq/rabbitmq-server/pull/4431)
+
  * Tracing and `idle_since` timestamps now reflect local time in RFC 3339 format. Previously
    a custom format was used for these timestamps and they always reflected UTC time.
 
@@ -246,6 +253,27 @@ This release includes all applicable [bug fixes that shipped in `3.9.x` releases
    GitHub issue: [#4408](https://github.com/rabbitmq/rabbitmq-server/pull/4408)
 
 
+### MQTT Plugin
+
+#### Enhancements
+
+ * Durable (QoS 1) subscriptions now can be backed by [quorum queues](https://www.rabbitmq.com/quorum-queues.html) if configured so.
+
+   This setting **can only be applied for new clusters**: existing durable classic
+   queues will not be converted. Enabling this setting in a cluster with existing
+   durable subscription data of MQTT clients will make it impossible for them to
+   subscribe without **explicit queue deletion** by the cluster operator.
+
+   To opt in to use quorum queues for durable MQTT subscriptions, use the `mqtt.durable_queue_type`
+   configuration key in `rabbitmq.conf`:
+
+   ``` ini
+   mqtt.durable_queue_type = quorum
+   ```
+
+   GitHub issue: [#4401](https://github.com/rabbitmq/rabbitmq-server/pull/4401)
+
+
 ### OAuth 2 AuthN and AuthZ Backend Plugin
 
 #### Enhancements