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https://issues.apache.org/jira/browse/CASSANDRA-4905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13665806#comment-13665806
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Michael Theroux commented on CASSANDRA-4905:
--------------------------------------------
To followup on my previous comment, I performed the test I described. The
results were quite incredible. I brought up three nodes that represented one
token range and its replicas. These were brought up from very recent
snapshots, so some inconsistency was expected. I ran the test twice with and
without the patch, and on the same data, and periodically monitored the number
of pending compaction tasks. Below you see a time that it was monitored, and
the number of pending compactions during that time
Without the Patch:
start: 10:30
11:22 - 196
12:33 - 112
13:19 - 1558
14:03 - 1579
14:48 - 1356
15:25 - 1181
16:49 - 752
17:30 - 657
17:52 - 548
18:56 - 202
19:36 - 29
01:50 - 0
With the patch:
start: 3:47
4:34 - 1
4:40 - 1
4:50 - 32
5:01 - 209
5:54 - 1
6:50 - 3 (all streaming from compaction complete)
6:54 - Repair complete, no compactions
Not only was this a very efficient repair from the point of view of the number
of compactions, it also completed in a little over 3 hours, which is equally as
dramatic (validation typically lasts several hours for us).
> Repair should exclude gcable tombstones from merkle-tree computation
> --------------------------------------------------------------------
>
> Key: CASSANDRA-4905
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4905
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Christian Spriegel
> Assignee: Sylvain Lebresne
> Fix For: 1.2.0 beta 3
>
> Attachments: 4905.txt
>
>
> Currently gcable tombstones get repaired if some replicas compacted already,
> but some are not compacted.
> This could be avoided by ignoring all gcable tombstones during merkle tree
> calculation.
> This was discussed with Sylvain on the mailing list:
> http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/repair-compaction-and-tombstone-rows-td7583481.html
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