Kirill Sizov created IGNITE-20445:
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Summary: 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
If a transaction was committed/aborted, but 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 such entries, no matter on primary or on any other
node, it performs write intent resolution and returns the correct result.
_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.
*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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