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https://issues.apache.org/jira/browse/CASSANDRA-7953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14958849#comment-14958849
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Fernando Gonçalves commented on CASSANDRA-7953:
-----------------------------------------------
We have experienced the same behaviour described on ticket
[https://issues.apache.org/jira/browse/CASSANDRA-10505]: "Once this happens in
multiple sstables, compacting them causes the duplication to grow. The more
this occurs, the worse the problem gets."
Basically, when we run the repair in the node, the compaction process starts
and never ends, many pending tasks, and the number of sstables of one table
grows exponentially (reaching 34k sstables). We use one column of the type
map<text, text>, LeveledStrategyCompaction, and many updates to this column.
The memory consumption grows a lot too. We decide to stop the repair process
and kill the node, because the latency grown a lot too and impact the whole
cluster. But we need to run repair again, because we kill one node and put a
new node on the cluster, and another node was impacted from this bug again, and
we need to repeated the process: kill the repair process, kill the node, start
a new node.
So we just created another table without using the collection map, but using
blob type instead, and migrate all the data for it - we are fine now: the
repair process and compaction finished successfully without big impact on
performance.
Please, give attention for this ticket, I think that its a major issue!
> RangeTombstones not merging during compaction
> ---------------------------------------------
>
> Key: CASSANDRA-7953
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7953
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Environment: Cassandra 2.1
> Reporter: Marcus Olsson
> Assignee: Branimir Lambov
> Priority: Minor
> Labels: compaction, deletes, tombstone
> Fix For: 2.1.x, 2.2.x
>
> Attachments: 0001-7953-v2.patch, CASSANDRA-7953-1.patch,
> CASSANDRA-7953.patch
>
>
> When performing a compaction on two sstables that contain the same
> RangeTombstone with different timestamps, the tombstones are not merged in
> the new sstable.
> This has been tested using cassandra 2.1 with the following table:
> {code}
> CREATE TABLE test(
> key text,
> column text,
> data text,
> PRIMARY KEY(key, column)
> );
> {code}
> And then doing the following:
> {code}
> INSERT INTO test (key, column, data) VALUES ("1", "1", "1"); // If the
> sstable only contains tombstones during compaction it seems that the sstable
> either gets removed or isn't created (but that could probably be a separate
> JIRA issue).
> INSERT INTO test (key, column, data) VALUES ("1", "2", "2"); // The inserts
> are not actually needed, since the deletes create tombstones either way.
> DELETE FROM test WHERE key="1" AND column="2";
> nodetool flush
> INSERT INTO test (key, column, data) VALUES ("1", "2", "2");
> DELETE FROM test WHERE key="1" AND column="2";
> nodetool flush
> nodetool compact
> {code}
> When checking with the SSTableExport tool two tombstones exists in the
> compacted sstable. This can be repeated, resulting in more and more
> tombstones.
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