Tommy Stendahl created CASSANDRA-10353:
------------------------------------------
Summary: 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
