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https://issues.apache.org/jira/browse/OAK-2106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14974132#comment-14974132
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Vikas Saurabh commented on OAK-2106:
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bq. Then it computes a separate average for each SECONDARY
[~tomek.rekawek], I think it's not a good idea to average out last 10 lag times
- this can potentially lead to wrong results when current lag is greater than
average (thus the algo would think that secondaries are more up to date than
they really are)
> Optimize reads from secondaries
> -------------------------------
>
> Key: OAK-2106
> URL: https://issues.apache.org/jira/browse/OAK-2106
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: core, mongomk
> Reporter: Marcel Reutegger
> Assignee: Marcel Reutegger
> Labels: performance, scalability
>
> OAK-1645 introduced support for reads from secondaries under certain
> conditions. The current implementation checks the _lastRev on a potentially
> cached parent document and reads from a secondary if it has not been
> modified in the last 6 hours. This timespan is somewhat arbitrary but
> reflects the assumption that the replication lag of a secondary shouldn't
> be more than 6 hours.
> This logic should be optimized to take the actual replication lag into
> account. MongoDB provides information about the replication lag with
> the command rs.status().
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