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https://issues.apache.org/jira/browse/CASSANDRA-12867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15630856#comment-15630856
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Kurt Greaves commented on CASSANDRA-12867:
------------------------------------------
{quote}We do have a small regression here. I say small, because any batch that
would hit this can be easily rewritten in a simpler way.{quote}
I just want to clarify that "regressions" such as this are not "small". It's a
behaviour that is expected to work, that now doesn't. If this got deployed, it
would cause people errors, which is never considered a small problem. No matter
how nonsensical the statements, if we allow it we should ensure it works.
Following on from this, we should test each case to ensure we don't hit this
regression again, not only the cases that we think "make sense". So while we're
here, can we add a test for the original example as well?
Thanks for the patch.
> Batch with multiple conditional updates for the same partition causes
> AssertionError
> ------------------------------------------------------------------------------------
>
> Key: CASSANDRA-12867
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12867
> Project: Cassandra
> Issue Type: Bug
> Components: CQL
> Reporter: Kurt Greaves
> Assignee: Sylvain Lebresne
> Attachments: 12867-3.0.patch
>
>
> Reproduced in 3.0.10 and 3.10. Used to work in 3.0.9 and earlier. Bug was
> introduced in CASSANDRA-12060.
> The following causes an AssertionError:
> {code}
> CREATE KEYSPACE test WITH replication = { 'class' : 'SimpleStrategy',
> 'replication_factor' : 1 };
> create table test.test (id int PRIMARY KEY, val text);
> BEGIN BATCH INSERT INTO test.test (id, val) VALUES (999, 'aaa') IF NOT
> EXISTS; INSERT INTO test.test (id, val) VALUES (999, 'ccc') IF NOT EXISTS;
> APPLY BATCH ;
> {code}
> Stack trace is as follows:
> {code}
> ERROR [Native-Transport-Requests-2] 2016-10-31 04:16:44,231 Message.java:622
> - Unexpected exception during request; channel = [id: 0x176e1c04,
> L:/127.0.0.1:9042 - R:/127.0.0.1:59743]
> java.lang.AssertionError: null
> at
> org.apache.cassandra.cql3.statements.CQL3CasRequest.setConditionsForRow(CQL3CasRequest.java:138)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.CQL3CasRequest.addExistsCondition(CQL3CasRequest.java:104)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.CQL3CasRequest.addNotExist(CQL3CasRequest.java:84)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.IfNotExistsCondition.addConditionsTo(IfNotExistsCondition.java:28)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.ModificationStatement.addConditions(ModificationStatement.java:482)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.BatchStatement.makeCasRequest(BatchStatement.java:434)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.BatchStatement.executeWithConditions(BatchStatement.java:379)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.BatchStatement.execute(BatchStatement.java:358)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.BatchStatement.execute(BatchStatement.java:346)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.BatchStatement.execute(BatchStatement.java:341)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.processStatement(QueryProcessor.java:218)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.process(QueryProcessor.java:249)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.process(QueryProcessor.java:234)
> ~[main/:na]
> at
> org.apache.cassandra.transport.messages.QueryMessage.execute(QueryMessage.java:115)
> ~[main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:516)
> [main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:409)
> [main/:na]
> at
> io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
> [netty-all-4.0.39.Final.jar:4.0.39.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:366)
> [netty-all-4.0.39.Final.jar:4.0.39.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext.access$600(AbstractChannelHandlerContext.java:35)
> [netty-all-4.0.39.Final.jar:4.0.39.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext$7.run(AbstractChannelHandlerContext.java:357)
> [netty-all-4.0.39.Final.jar:4.0.39.Final]
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> [na:1.8.0_102]
> at
> org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$FutureTask.run(AbstractLocalAwareExecutorService.java:162)
> [main/:na]
> at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:109)
> [main/:na]
> at java.lang.Thread.run(Thread.java:745) [na:1.8.0_102]
> {code}
> The problem is that previous will receive a value after the first statement
> in the batch is evaluated in BatchStatement.makeCasRequest. I can't see any
> reason why we have this assertion, it seems to me that it's unnecessary.
> Removing it fixes the problem (obviously) but I'm not sure if it breaks
> something else, or if this is an intended failure case (in which case it
> should be caught earlier on).
> Relevant code is as follows:
> {code:title=CQL3CasRequest.java}
> private void setConditionsForRow(Clustering clustering, RowCondition
> condition)
> {
> if (clustering == Clustering.STATIC_CLUSTERING)
> {
> assert staticConditions == null;
> staticConditions = condition;
> }
> else
> {
> RowCondition previous = conditions.put(clustering, condition);
> assert previous == null;
> }
> }
> {code}
> I've attached a patch that fixes the issue by removing the assert
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