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https://issues.apache.org/jira/browse/CASSANDRA-10353?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Yuki Morishita resolved CASSANDRA-10353.
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Resolution: Duplicate
> NULL in compaction_history in 2.2.1
> -----------------------------------
>
> Key: CASSANDRA-10353
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10353
> Project: Cassandra
> Issue Type: Bug
> Reporter: Tommy Stendahl
>
> While doing some tests on 2.2.1 I found a problem with a null value in the
> compaction_history table that results in a nullpointer exception when doing
> 'nodetool compactionhistory'.
> {quote}
> $ ccm node1 nodetool compactionhistory
> Compaction History:
> error: null
> -- StackTrace --
> java.lang.NullPointerException
> at com.google.common.base.Joiner$MapJoiner.join(Joiner.java:330)
> at org.apache.cassandra.utils.FBUtilities.toString(FBUtilities.java:477)
> at
> org.apache.cassandra.db.compaction.CompactionHistoryTabularData.from(CompactionHistoryTabularData.java:78)
> at
> org.apache.cassandra.db.SystemKeyspace.getCompactionHistory(SystemKeyspace.java:425)
> at
> org.apache.cassandra.db.compaction.CompactionManager.getCompactionHistory(CompactionManager.java:1492)
> {quote}
> The problem is the null value in the rows_merged column.
> {quote}
> cqlsh> SELECT * FROM system.compaction_history ;
> id | bytes_in | bytes_out |
> columnfamily_name | compacted_at | keyspace_name |
> rows_merged
> --------------------------------------+----------+-----------+-------------------------+--------------------------+---------------+--------------------
> 86548100-5adf-11e5-a4f4-29d398af617a | 366 | 64 |
> compactions_in_progress | 2015-09-14 12:52:58+0000 | system |
> \{2: 2}
> 9ff24610-5adf-11e5-a4f4-29d398af617a | 30 | 0 |
> bar | 2015-09-14 12:53:41+0000 | foo | null
> e4ffb130-5ade-11e5-a4f4-29d398af617a | 366 | 64 |
> compactions_in_progress | 2015-09-14 12:48:27+0000 | system |
> \{2: 2}
> {quote}
> After some more testing and digging in the code I realised that this is the
> result of a compaction where all sstables are dropped (i.e. no new sstable is
> created).
> I tried to recreate this using 2.1.9 and found that there where nothing
> inserted into the compaction_history table if the same thing happens. That is
> due to a check in CompactionTask.runMayThrow() line 181.
> {code}
> if (!iter.hasNext())
> {
> // don't mark compacted in the finally block, since if there _is_
> nondeleted data,
> // we need to sync it (via closeAndOpen) first, so there is no period
> during which
> // a crash could cause data loss.
> cfs.markObsolete(sstables, compactionType);
> return;
> }
> {code}
> The result of the return here is that we end the compaction without inserting
> anything in the compaction_history table, 2.2.1 does not have this logic and
> will insert the null value.
> Not sure what the best solution would be:
> 1. Implement the same behaviour as in 2.1.9 and skip inserting anything into
> compaction_history.
> 2. Make sure we insert a more sensible value then null, but I'm not sure what
> that value would be.
> 3. Have nodetool handle the null value without a nullpointer exception.
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