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https://issues.apache.org/jira/browse/IGNITE-20445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17773954#comment-17773954
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Vladislav Pyatkov commented on IGNITE-20445:
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Merged 228b5be6e3176ce40982b41f0dd3cf5c96452b09
> Clean up write intents for RW transaction on replication group nodes
> --------------------------------------------------------------------
>
> Key: IGNITE-20445
> URL: https://issues.apache.org/jira/browse/IGNITE-20445
> Project: Ignite
> Issue Type: Task
> Reporter: Kirill Sizov
> Assignee: Kirill Sizov
> Priority: Major
> Labels: ignite-3
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> If a transaction was committed/aborted and for any reason the cleanup
> operation was not performed on a node, the write intent entries would still
> be present in the storage.
> When an RO transaction sees write intents, no matter on primary or on any
> other node, it performs write intent resolution and returns the correct
> result.
> When an RW transaction sees write intents, we can get an exception.
> _Imagine the case where a finished transaction left its write intents in the
> storage of all nodes A, B and C. A is primary._
> _An RO transaction is executed on the primary A, it kicks off an async
> cleanup (IGNITE-20041)._
> _The cleanup is a local task (not distributed to the replication group), thus
> only the A's storage is cleaned. B and C storages still contain the same
> write intent._
> _Now an RW transaction starts. It sees no write intents on A, executes its
> action and the action is replicated to B and C. Execution of this task on B
> and C will result in a storage exception since it's not allowed to have more
> than one write intent per row._
> *Definition of Done*
> The nodes of the replication group should perform cleanup of their storages
> when they receive an UpdateCommand, before adding new write intents.
> *Implementation details*
> We can extend the update command with the timestamp of the latest commit on
> primary.
> If the nodes of the replication group see a write intent in their storage,
> they will:
> * +commit+ the write intent if the UpdateCommand`s latestCommitTimestamp is
> greater than the commit timestamp of latest committed entry.
> * +abort+ the write intent if he UpdateCommand`s latestCommitTimestamp is
> equal to the commit timestamp of latest committed entry.
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