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https://issues.apache.org/jira/browse/SOLR-9446?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15439296#comment-15439296
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Pushkar Raste commented on SOLR-9446:
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I can think of couple of ways two solve it using fingerprint comparsion
# Add a fingerprint check in {{SyncStratergy.syncToMe()}} and request replica
to sync only if fingperint does not match
# Add a fingerprint check in {{RecoveryStratergy.doRecovery()}} and initiate
recovery only if fingerprint check does not match
# Add a fingerprint check in {{PeerSync.sync()}} to check if we are already in
sync
I think we almost always try PeerSync before trying replication so *#3*, should
work.
> Just replicated index goes into replication recovery on leader failure even
> there index was not changed
> -------------------------------------------------------------------------------------------------------
>
> Key: SOLR-9446
> URL: https://issues.apache.org/jira/browse/SOLR-9446
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Components: replication (java)
> Reporter: Pushkar Raste
> Priority: Minor
>
> We noticed this issue while migrating solr index from machines {{A1, A2 and
> A3}} to {{B1, B2, B3}}. We followed following steps (and there were no
> updates during the migration process).
> * Index had replicas on machines {{A1, A2, A3}}. Let's say {{A1}} was the
> leader at the time
> * We added 3 more replicas {{B1, B2 and B3}}. These nodes synced with the by
> replication. These fresh nodes do not have tlogs.
> * We shut down one of the old nodes ({{A3}}).
> * We then shut down the leader ({{A1}})
> * New leader got elected (let's say {{A2}}) became the new leader
> * Leader asked all the replicas to sync with it
> * Fresh nodes (ones without tlogs), first tried PeerSync but since there was
> no frame of reference, PeerSync failed and fresh nodes fail back on to try
> replication
> Although replication would not copy all the segments again, it seems like we
> can short circuit sync to put nodes back in active state as soon as possible.
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