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https://issues.apache.org/jira/browse/CASSANDRA-8090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14179899#comment-14179899
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Benjamin Lerer commented on CASSANDRA-8090:
-------------------------------------------
{quote}Ok. I'm still bugged by the fact we now have to copy the selectors even
when there is no aggregations, but I don't have a very good alternative to
suggest so that will do for now.{quote}
I do not like it so much either but I did not find a nice approach to avoid it.
{quote}I'd rename containsNoAggregateSelectorFactories to
containsAggregateFunction: we use it only negated and the double-negation is
harder to read (I also don't think the "SelectorFactories" part adds much since
the method is on SelectorFactories but that's more of a personal taste).
Similarly, containsOnlyAggretateSelectorFactories could just be
containsScalarFunction.{quote}
I have simplified the name of the methods but I could not renamed as you
suggested as it does not really have the same meaning.
What we want is that either all the selectors are the one of aggregate
functions {{containsOnlyAggretateFunctions}} or that we do not have any
aggregate (which does not means that it is a scalar function, it can be a
column value) {{containsNoAggregateFunctions}}.
I have a new patch
[here|https://github.com/blerer/cassandra/compare/CASSANDRA-8090], were I
renamed the 2 methods and moves the selection classes to a new package.
I also noticed that the function selectors were creating an Iterator (by using
a for each instead of a normal for) and a List to hold (the function arguments)
for each call (e.g. 10 000 row read with a function will result in 20 000
object created). So I optimized them by reusing the List and using normal for
loop.
> NullPointerException when using prepared statements
> ---------------------------------------------------
>
> Key: CASSANDRA-8090
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8090
> Project: Cassandra
> Issue Type: Bug
> Reporter: Carl Yeksigian
> Assignee: Benjamin Lerer
> Fix For: 3.0
>
>
> Due to the changes in CASSANDRA-4914, using a prepared statement from
> multiple threads leads to a race condition where the simple selection may be
> reset from a different thread, causing the following NPE:
> {noformat}
> java.lang.NullPointerException: null
> at org.apache.cassandra.cql3.ResultSet.addRow(ResultSet.java:63)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.Selection$ResultSetBuilder.build(Selection.java:372)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.SelectStatement.process(SelectStatement.java:1120)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.SelectStatement.processResults(SelectStatement.java:283)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.SelectStatement.execute(SelectStatement.java:260)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.SelectStatement.execute(SelectStatement.java:213)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.statements.SelectStatement.execute(SelectStatement.java:63)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.processStatement(QueryProcessor.java:226)
> ~[main/:na]
> at
> org.apache.cassandra.cql3.QueryProcessor.processPrepared(QueryProcessor.java:481)
> ~[main/:na]
> at
> org.apache.cassandra.transport.messages.ExecuteMessage.execute(ExecuteMessage.java:133)
> ~[main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:438)
> [main/:na]
> at
> org.apache.cassandra.transport.Message$Dispatcher.channelRead0(Message.java:334)
> [main/:na]
> at
> io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
> [netty-all-4.0.23.Final.jar:4.0.23.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:333)
> [netty-all-4.0.23.Final.jar:4.0.23.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext.access$700(AbstractChannelHandlerContext.java:32)
> [netty-all-4.0.23.Final.jar:4.0.23.Final]
> at
> io.netty.channel.AbstractChannelHandlerContext$8.run(AbstractChannelHandlerContext.java:324)
> [netty-all-4.0.23.Final.jar:4.0.23.Final]
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
> [na:1.7.0_67]
> at
> org.apache.cassandra.concurrent.AbstractTracingAwareExecutorService$FutureTask.run(AbstractTracingAwareExecutorService.java:163)
> [main/:na]
> at org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:103)
> [main/:na]
> at java.lang.Thread.run(Thread.java:745) [na:1.7.0_67]
> {noformat}
> Reproduced this using the stress tool:
> {noformat}
> ./tools/bin/cassandra-stress user profile=tools/cqlstress-example.yaml
> ops\(insert=1,simple1=1\)
> {noformat}
> You'll need to change the {noformat}select:{noformat} line to be /1000 to
> prevent the illegal query exceptions.
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