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https://issues.apache.org/jira/browse/CASSANDRA-14861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16677114#comment-16677114
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Sam Tunnicliffe commented on CASSANDRA-14861:
---------------------------------------------
+1
> sstable min/max metadata can cause data loss
> --------------------------------------------
>
> Key: CASSANDRA-14861
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14861
> Project: Cassandra
> Issue Type: Bug
> Reporter: Blake Eggleston
> Assignee: Blake Eggleston
> Priority: Major
> Fix For: 3.0.18, 3.11.4, 4.0
>
>
> There’s a bug in the way we filter sstables in the read path that can cause
> sstables containing relevant range tombstones to be excluded from reads. This
> can cause data resurrection for an individual read, and if compaction timing
> is right, permanent resurrection via read repair.
> We track the min and max clustering values when writing an sstable so we can
> avoid reading from sstables that don’t contain the clustering values we’re
> looking for in a given read. The min max for each clustering column are
> updated for each row / RT marker we write. In the case of range tombstones
> markers though, we only update the min max for the clustering values they
> contain, which is almost never the full set of clustering values. This leaves
> a min/max that are above/below (respectively) the real ranges covered by the
> range tombstone contained in the sstable.
> For instance, assume we’re writing an sstable for a table with 3 clustering
> values. The current min clustering is 5:6:7. We write an RT marker for a
> range tombstone that deletes any row with the value 4 in the first clustering
> value so the open marker is [4:]. This would make the new min clustering
> 4:6:7 when it should really be 4:. If we do a read for clustering values of
> 4:5 and lower, we’ll exclude this sstable and it’s range tombstone,
> resurrecting any data there that this tombstone would have deleted.
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