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https://issues.apache.org/jira/browse/CASSANDRA-12884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aleksey Yeschenko updated CASSANDRA-12884:
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Reviewer: (was: Aleksey Yeschenko)
> Batch logic can lead to unbalanced use of system.batches
> --------------------------------------------------------
>
> Key: CASSANDRA-12884
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12884
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Adam Hattrell
> Assignee: Joshua McKenzie
> Fix For: 3.0.x, 3.11.x
>
>
> It looks as though there are some odd edge cases in how we distribute the
> copies in system.batches.
> The main issue is in the filter method for
> org.apache.cassandra.batchlog.BatchlogManager
> {code:java}
> if (validated.size() - validated.get(localRack).size() >= 2)
> {
> // we have enough endpoints in other racks
> validated.removeAll(localRack);
> }
> if (validated.keySet().size() == 1)
> {
> // we have only 1 `other` rack
> Collection otherRack =
> Iterables.getOnlyElement(validated.asMap().values());
>
> return Lists.newArrayList(Iterables.limit(otherRack, 2));
> }
> {code}
> So with one or two racks we just return the first 2 entries in the list.
> There's no shuffle or randomisation here.
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