Repository: hbase Updated Branches: refs/heads/master d016338e4 -> 29c46c483
HBASE-15985 clarify promises about edits from replication in ref guide Signed-off-by: Andrew Purtell <apurt...@apache.org> Project: http://git-wip-us.apache.org/repos/asf/hbase/repo Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/29c46c48 Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/29c46c48 Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/29c46c48 Branch: refs/heads/master Commit: 29c46c4834a3f96e9fca33cb16bc7f3748fcd60c Parents: d016338 Author: Sean Busbey <bus...@apache.org> Authored: Tue Jun 7 17:16:55 2016 -0500 Committer: Sean Busbey <bus...@apache.org> Committed: Tue Jul 5 13:03:18 2016 -0500 ---------------------------------------------------------------------- src/main/asciidoc/_chapters/ops_mgt.adoc | 8 ++++++++ 1 file changed, 8 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hbase/blob/29c46c48/src/main/asciidoc/_chapters/ops_mgt.adoc ---------------------------------------------------------------------- diff --git a/src/main/asciidoc/_chapters/ops_mgt.adoc b/src/main/asciidoc/_chapters/ops_mgt.adoc index 13449c1..6e84237 100644 --- a/src/main/asciidoc/_chapters/ops_mgt.adoc +++ b/src/main/asciidoc/_chapters/ops_mgt.adoc @@ -1320,6 +1320,14 @@ The master cluster relies on randomization to attempt to balance the stream of r It is expected that the slave cluster has storage capacity to hold the replicated data, as well as any data it is responsible for ingesting. If a slave cluster does run out of room, or is inaccessible for other reasons, it throws an error and the master retains the WAL and retries the replication at intervals. +.Consistency Across Replicated Clusters +[WARNING] +==== +How your application builds on top of the HBase API matters when replication is in play. HBase's replication system provides at-least-once delivery of client edits for an enabled column family to each configured destination cluster. In the event of failure to reach a given destination, the replication system will retry sending edits in a way that might repeat a given message. Further more, there is not a guaranteed order of delivery for client edits. In the event of a RegionServer failing, recovery of the replication queue happens independent of recovery of the individual regions that server was previously handling. This means that it is possible for the not-yet-replicated edits to be serviced by a RegionServer that is currently slower to replicate than the one that handles edits from after the failure. + +The combination of these two properties (at-least-once delivery and the lack of message ordering) means that some destination clusters may end up in a different state if your application makes use of operations that are not idempotent, e.g. Increments. +==== + .Terminology Changes [NOTE] ====
