From 19feb720fbad5bba0e4f94cfc4b235a8f533f4ae Mon Sep 17 00:00:00 2001 From: Bob Grabar Date: Mon, 20 Aug 2012 16:47:48 -0400 Subject: [PATCH] DOCS-378 added note on idempotency of oplogs --- source/core/replication-internals.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/source/core/replication-internals.txt b/source/core/replication-internals.txt index 5be96a9232b..c8babc280fa 100644 --- a/source/core/replication-internals.txt +++ b/source/core/replication-internals.txt @@ -30,6 +30,16 @@ exceptional situations may cause secondaries to lag behind further. See All members send heartbeats (pings) to all other members in the set and can import operations to the local oplog from any other member in the set. +Replica set oplog operations are :term:`idempotent`. Idempotency is +required because of the following operations: + +- initial sync +- post-rollback catch-up +- sharding chunk migrations + + + .. TODO. Verify that "sharding chunk migrations" (above) requires idempotency + For more information about the oplog, see :ref:`oplog sizing `. .. In 2.0, replicas would import entries from the member lowest