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https://issues.apache.org/jira/browse/SOLR-8227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15048176#comment-15048176
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Ayon Sinha commented on SOLR-8227:
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According to the principles of C,P or CAP, a write by a leader is complete only
when all replicas have ack-ed an update to its tlog. i.e. unless the update
(add/delete) shows up on all active replicas the write is not complete (this is
exactly what is documented in SOLR-8225, leader gets stuck). This means that
any recovering replica whether it gets the updates from leader or an active
replica will be trailing them updates until completely caught up.
Please explain the condition under which a leader has a successful update where
an active replica does not.
> Recovering replicas should be able to recover from any active replica
> ---------------------------------------------------------------------
>
> Key: SOLR-8227
> URL: https://issues.apache.org/jira/browse/SOLR-8227
> Project: Solr
> Issue Type: Improvement
> Reporter: Varun Thacker
>
> Currently when a replica goes into recovery it uses the leader to recover. It
> first tries to do a PeerSync. If thats not successful it does a
> replication. Most of the times it ends up doing a full replication because
> segment merging, autoCommits causing segments to be formed differently on the
> replicas ( We should explore improving that in another issue ) .
> But when many replicas are recovering and hitting the leader, the leader can
> become a bottleneck. Since Solr is a CP system , we should be able to recover
> from any of the 'active' replicas instead of just the leader.
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