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Alexander Lapin updated IGNITE-20445: ------------------------------------- Reviewer: Vladislav Pyatkov (was: Alexander Lapin) > 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: 0.5h > 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. -- This message was sent by Atlassian Jira (v8.20.10#820010)