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https://issues.apache.org/jira/browse/CASSANDRA-12694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15536170#comment-15536170
]
Alex Petrov commented on CASSANDRA-12694:
-----------------------------------------
Thanks for the pointer to the commit. Although the problem was not really
caused by this addition, it just got surfaced. What we expect there is correct
and protects users from reading data from the corrupt SSTable. In the case of
an empty row we would have liveness (which is used to distinguish empty from
dead row [more details
here|https://github.com/apache/cassandra/blob/cassandra-3.0/src/java/org/apache/cassandra/db/rows/Row.java#L71-L86](.
What happens is that we're following a read path that reads out only the
columns that are affected by the LWT (and this column was never set), which
results into this check failing, since there's no liveness that would confirm
that this row exists but is empty. In fact, we'll run into the same situation
if we use "regular" (not LWT) update in the first place, like that:
{code}
update test.lwt_corruption_test set last_updated = 555 where test_id = 'test3';
update test.lwt_corruption_test set last_updated = 555 where test_id = 'test3'
if message_id = null;
;; would result into the same error
{code}
However, running the LWT with a column that actually exists would result into
successful LWT:
{code}
update test.lwt_corruption_test set last_updated = 555 where test_id = 'test3'
if message_id = null and last_updated = 555;
{code}
Now, {{last_updated}} will be returned and non-empty.
> PAXOS Update Corrupted empty row exception
> ------------------------------------------
>
> Key: CASSANDRA-12694
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12694
> Project: Cassandra
> Issue Type: Bug
> Components: Local Write-Read Paths
> Environment: 3 node cluster using RF=3 running on cassandra 3.7
> Reporter: Cameron Zemek
> Assignee: Alex Petrov
>
> {noformat}
> cqlsh> create table test.test (test_id TEXT, last_updated TIMESTAMP,
> message_id TEXT, PRIMARY KEY(test_id));
> update test.test set last_updated = 1474494363669 where test_id = 'test1' if
> message_id = null;
> {noformat}
> Then nodetool flush on the all 3 nodes.
> {noformat}
> cqlsh> update test.test set last_updated = 1474494363669 where test_id =
> 'test1' if message_id = null;
> ServerError: <ErrorMessage code=0000 [Server error] message="java.io.IOError:
> java.io.IOException: Corrupt empty row found in unfiltered partition">
> {noformat}
> From cassandra log
> {noformat}
> ERROR [SharedPool-Worker-1] 2016-09-23 12:09:13,179 Message.java:611 -
> Unexpected exception during request; channel = [id: 0x7a22599e,
> L:/127.0.0.1:9042 - R:/127.0.0.1:58297]
> java.io.IOError: java.io.IOException: Corrupt empty row found in unfiltered
> partition
> at
> org.apache.cassandra.db.rows.UnfilteredRowIteratorSerializer$1.computeNext(UnfilteredRowIteratorSerializer.java:224)
> ~[main/:na]
> at
> org.apache.cassandra.db.rows.UnfilteredRowIteratorSerializer$1.computeNext(UnfilteredRowIteratorSerializer.java:212)
> ~[main/:na]
> at
> org.apache.cassandra.utils.AbstractIterator.hasNext(AbstractIterator.java:47)
> ~[main/:na]
> at
> org.apache.cassandra.db.rows.UnfilteredRowIterators.digest(UnfilteredRowIterators.java:125)
> ~[main/:na]
> at
> org.apache.cassandra.db.partitions.UnfilteredPartitionIterators.digest(UnfilteredPartitionIterators.java:249)
> ~[main/:na]
> at
> org.apache.cassandra.db.ReadResponse.makeDigest(ReadResponse.java:87)
> ~[main/:na]
> at
> org.apache.cassandra.db.ReadResponse$DataResponse.digest(ReadResponse.java:192)
> ~[main/:na]
> at
> org.apache.cassandra.service.DigestResolver.resolve(DigestResolver.java:80)
> ~[main/:na]
> at
> org.apache.cassandra.service.ReadCallback.get(ReadCallback.java:139)
> ~[main/:na]
> at
> org.apache.cassandra.service.AbstractReadExecutor.get(AbstractReadExecutor.java:145)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy$SinglePartitionReadLifecycle.awaitResultsAndRetryOnDigestMismatch(StorageProxy.java:1714)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.fetchRows(StorageProxy.java:1663)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.readRegular(StorageProxy.java:1604)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.read(StorageProxy.java:1523)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.readOne(StorageProxy.java:1497)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.readOne(StorageProxy.java:1491)
> ~[main/:na]
> at
> org.apache.cassandra.service.StorageProxy.cas(StorageProxy.java:249)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.ModificationStatement.executeWithCondition(ModificationStatement.java:441)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.ModificationStatement.execute(ModificationStatement.java:416)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.processStatement(QueryProcessor.java:208)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.process(QueryProcessor.java:239)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.process(QueryProcessor.java:224)
> ~[main/:na]
> at
> org.apache.cassandra.transport.messages.QueryMessage.execute(QueryMessage.java:115)
> ~[main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:507)
> [main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:401)
> [main/:na]
> {noformat}
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