Tomek Rękawek created OAK-4069:
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Summary: Use read concern majority when connected to a replica set
Key: OAK-4069
URL: https://issues.apache.org/jira/browse/OAK-4069
Project: Jackrabbit Oak
Issue Type: Improvement
Components: mongomk
Reporter: Tomek Rękawek
Fix For: 1.6
Mongo 3.2 introduces new query option: {{readConcern}}. It allows to read only
these changes that have been already committed to the majority of secondary
instances.
It prevents stale reads - a situation in which a change has been committed on
the primary (and read from it), but due to the network partition a new primary
is elected and the change is rolled back.
We should use this new option (together with {{w:majority}} implemented in
OAK-3559) when running Oak on MongoDB replica set.
References:
* [Jepsen: MongoDB stale
reads|https://aphyr.com/posts/322-jepsen-mongodb-stale-reads]
* [MongoDB documentation: Read Concern
in|https://docs.mongodb.org/manual/reference/read-concern/]
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