[jira] [Assigned] (IGNITE-22916) Validate Metastorage for divergency during join

["Vladimir Pligin (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IGNITE-22916?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vladimir Pligin reassigned IGNITE-22916:
----------------------------------------

    Assignee: Roman Puchkovskiy

> Validate Metastorage for divergency during join
> -----------------------------------------------
>
>                 Key: IGNITE-22916
>                 URL: https://issues.apache.org/jira/browse/IGNITE-22916
>             Project: Ignite
>          Issue Type: Improvement
>            Reporter: Roman Puchkovskiy
>            Assignee: Roman Puchkovskiy
>            Priority: Major
>              Labels: iep-128, ignite-3
>
> A joining node will take <revision, hash> for the latest command it has applied on Metastorage recovery as <nodeRevision, nodeHash> and will use it when validating against the MG leader. It will ask the MG leader to provide its current history in the form of <revision, hash> pairs. Let’s denote min and max revisions in the leader’s history as minRevision and maxRevision and leader’s hash for revision R as leaderHash(R). Outcomes:
>  # minRevision <= nodeRevision <= maxRevision and leaderHash(nodeRevision) = nodeHash -> node is allowed to join
>  # minRevision <= nodeRevision <= maxRevision and leaderHash(nodeRevision) <> nodeHash -> the node is not allowed to join
>  # nodeRevision > maxRevision -> disallow join (maybe it actually diverged and the leader is going to grow its history in another direction while the current node is joining)
>  # nodeRevision < minRevision (some history is removed due to compaction) -> we don’t know if it diverged -> the node is not allowed to join



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