From 5b08a2792bf48a45ed3a2c89d5172c263107d5a5 Mon Sep 17 00:00:00 2001 From: DeDe Morton Date: Mon, 27 Feb 2017 19:27:49 -0800 Subject: [PATCH] Add at least once delivery to persistent queue docs Fixes #6761 --- docs/static/persistent-queues.asciidoc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/docs/static/persistent-queues.asciidoc b/docs/static/persistent-queues.asciidoc index 547ba8945..357a18757 100644 --- a/docs/static/persistent-queues.asciidoc +++ b/docs/static/persistent-queues.asciidoc @@ -19,10 +19,14 @@ Instead of deploying and managing a message broker, such as Redis, RabbitMQ, or Apache Kafka, to facilitate a buffered publish-subscriber model, you can enable persistent queues to buffer events on disk and remove the message broker. -In summary, the two benefits of enabling persistent queues are as follows: +In summary, the benefits of enabling persistent queues are as follows: * Provides protection from in-flight message loss when the Logstash process is abnormally terminated. * Absorbs bursts of events without needing an external buffering mechanism like Redis or Apache Kafka. +* Provides an at-least-once message delivery guarantee. If Logstash is restarted while events are +in-flight, Logstash will attempt to deliver messages stored in the persistent queue until delivery +succeeds at least once. In other words, messages stored in the persistent queue may be duplicated, but +not lost. [[persistent-queues-limitations]] ==== Limitations of Persistent Queues