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https://issues.apache.org/jira/browse/OAK-4069?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tomek Rękawek updated OAK-4069:
-------------------------------
Description:
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-3554) 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/]
was:
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/]
> 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
> Assignee: Tomek Rękawek
> Labels: resilience
> Fix For: 1.6, 1.5.16
>
>
> 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-3554) 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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