[jira] [Comment Edited] (IGNITE-22467) PlacementDriver should have a method to return an assignments for a specified partition

["Vladislav Pyatkov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-22467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17856738#comment-17856738 ] 

Vladislav Pyatkov edited comment on IGNITE-22467 at 6/21/24 12:47 PM:
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I reviewed the patch, and it agrees with my thoughts. But just be aware that a primary replica might not be part of assignments. It can happen after a rebalance where we intentionally hold a primary until the lease is expired.


was (Author: v.pyatkov):
I reviewd the patch and it agrees with my thoughts. But just be aware, a primary replica might be not a part of assignments. It can happen after rebalance where we intentanaly hold a primary until lease is expired.

> PlacementDriver should have a method to return an assignments for a specified partition
> ---------------------------------------------------------------------------------------
>
>                 Key: IGNITE-22467
>                 URL: https://issues.apache.org/jira/browse/IGNITE-22467
>             Project: Ignite
>          Issue Type: Improvement
>            Reporter: Alexander Lapin
>            Assignee: Alexander Lapin
>            Priority: Major
>              Labels: ignite-3
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> h3. Motivation
> In order to implement read from backup logic it's required to provide an ability to retrieve assignments at best-effort manner.
> h3. Definition of Done
> Following method should be added to the PlacementDriver
> {code:java}
> /**
>  * Returns the future with either newest available tokenized assignments for the specified replication group id or {@code null} if
>  * there are no such assignments. The future will be completed after clusterTime (meta storage safe time) will become greater or equal
>  * to the clusterTimeToAwait parameter.
>  *
>  * @param replicationGroupId Replication group Id.
>  * @param clusterTimeToAwait Cluster time to await.
>  * @return Tokenized assignments.
>  */
> CompletableFuture<TokenizedAssignments> getAssignments(ReplicationGroupId replicationGroupId, HybridTimestamp clusterTimeToAwait); {code}
> TokenizedAssignments is a common set of nodes along with associated token that allows to easely understand whether assignments were changed or not.
> {code:java}
> /**
>  * Set of nodes along with associated token that is guaranteed to be changed if the set was changed.
>  */
> public interface TokenizedAssignments extends Serializable {
>     /** Returns a set of nodes, represented by this assignments instance. */
>     Set<Assignment> nodes();
>     /** Returns a token associated with given assignments that is guaranteed to be changed if assignments were changed. */
>     long token();
> } {code}



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