From 5eec74132750f4119b1b761e7607aeee83928a67 Mon Sep 17 00:00:00 2001 From: Will Currie Date: Wed, 16 Jan 2019 06:28:05 +1100 Subject: [PATCH] Add Why Is "Connect to Replica" mode preferred? --- doc/questions.md | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/doc/questions.md b/doc/questions.md index be6eab0..7585bc7 100644 --- a/doc/questions.md +++ b/doc/questions.md @@ -28,3 +28,9 @@ It is therefore unlikely that `gh-ost` will support this behavior. Yes. TL;DR if running all on same replica/master, make sure to provide `--replica-server-id`. [Read more](cheatsheet.md#concurrent-migrations) # Why + +### Why Is the "Connect to Replica" mode preferred? + +To avoid placing extra load on the master. `gh-ost` connects as a replication client. Each additional replica adds some load to the master. + +To monitor replication lag from a replica. This makes the replication lag throttle, `--max-lag-millis`, more representative of the lag experienced by other replicas following the master (perhaps N levels deep in a tree of replicas).