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https://issues.apache.org/jira/browse/CASSANDRA-11427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15268516#comment-15268516
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Sylvain Lebresne commented on CASSANDRA-11427:
----------------------------------------------
Alright. It's been there forever and you're the first to bring it up so I don't
entirely buy that it confuses people that much, but it does bring consistency
between single partition and range queries and isn't very risky, so went ahead
and committed to 2.2. Thanks.
> Range slice queries CL > ONE trigger read-repair of purgeable tombstones
> ------------------------------------------------------------------------
>
> Key: CASSANDRA-11427
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11427
> Project: Cassandra
> Issue Type: Bug
> Reporter: Stefan Podkowinski
> Assignee: Stefan Podkowinski
> Priority: Minor
> Fix For: 2.2.7
>
> Attachments: 11427-2.1.patch, 11427-2.2_v2.patch
>
>
> Range queries will trigger read repairs for purgeable tombstones on hosts
> that already compacted given tombstones. Clusters with periodical jobs for
> scanning data ranges will likely see tombstones ressurected through RRs just
> to have them compacted again later at the destination host.
> Executing range queries (e.g. for reading token ranges) will compare the
> actual data instead of using digests when executed with CL > ONE. Responses
> will be consolidated by {{RangeSliceResponseResolver.Reducer}}, where the
> result of {{RowDataResolver.resolveSuperset}} is used as the reference
> version for the results. {{RowDataResolver.scheduleRepairs}} will then send
> the superset to all nodes that returned a different result before.
> Unfortunately this does also involve cases where the superset is just made up
> of purgeable tombstone(s) that already have been compacted on the other
> nodes. In this case a read-repair will be triggered for transfering the
> purgeable tombstones to all other nodes nodes that returned an empty result.
> The issue can be reproduced with the provided dtest or manually using the
> following steps:
> {noformat}
> create keyspace test1 with replication = { 'class' : 'SimpleStrategy',
> 'replication_factor' : 2 };
> use test1;
> create table test1 ( a text, b text, primary key(a, b) ) WITH compaction =
> {'class': 'SizeTieredCompactionStrategy', 'enabled': 'false'} AND
> dclocal_read_repair_chance = 0 AND gc_grace_seconds = 0;
> delete from test1 where a = 'a';
> {noformat}
> {noformat}
> ccm flush;
> ccm node2 compact;
> {noformat}
> {noformat}
> use test1;
> consistency all;
> tracing on;
> select * from test1;
> {noformat}
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