Hi Angelo,
Thank you so much for your advice.
Shame on me.
I didn't realize that error was from the set.
It works now.
Sorry for having such a stupid question.
On Wed, Sep 29, 2021 at 3:19 PM Angelo Polo <language.de...@gmail.com>
wrote:
> Hi Yu-Wei,
>
> Collections#emptySet returns an immutable Set, so it should be
> mutations.add(mutation);
> that's throwing the UnsupportedOperationException rather than anything
> related to C*.
>
> If you're going to add something to a set later, use the regular
> constructor. Most likely HashSet:
> new HashSet<>();
>
> Best,
> Angelo
>
> On Wed, Sep 29, 2021 at 3:48 AM Yu-Wei Su <plenty...@scalar-labs.com>
> wrote:
>
>> Hi,
>>
>> I am thinking of using the Cassandra trigger to delete or update data
>> right after they are inserted.
>>
>> First, I tried deleting the data.
>>
>> This is my table.
>>
>> ```
>> CREATE TABLE mykeyspace.mytable (
>> mycolumn text PRIMARY KEY
>> )
>> ```
>>
>> and this is my trigger
>>
>> ```
>> public class MyTrigger implements ITrigger {
>> public Collection<Mutation> augment(Partition partition) {
>> Collection<Mutation> mutations = Collections.emptySet();
>>
>> PartitionUpdate.SimpleBuilder partitionUpdateBuilder = Mutation
>> .simpleBuilder(partition.metadata().ksName,
>> partition.partitionKey())
>> .update(partition.metadata());
>>
>> Row.SimpleBuilder rowBuilder =
>> partitionUpdateBuilder.row(Clustering.EMPTY);
>>
>> rowBuilder.delete();
>>
>> Mutation mutation = partitionUpdateBuilder.buildAsMutation();
>>
>> mutations.add(mutation);
>>
>> return mutations;
>> }
>> }
>> ```
>>
>> then, I got this error message (/var/log/cassandra/system.log) at
>> run-time.
>>
>>
>> ```
>> ERROR [Native-Transport-Requests-1] 2021-09-28 06:49:12,748
>> ErrorMessage.java:384 - Unexpected exception during request
>> java.lang.RuntimeException: Exception while executing trigger on table
>> with ID: 27a4dfa0-2028-11ec-a91c-6d2c86545d91
>> at
>> org.apache.cassandra.triggers.TriggerExecutor.executeInternal(TriggerExecutor.java:246)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.triggers.TriggerExecutor.execute(TriggerExecutor.java:124)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.service.StorageProxy.mutateWithTriggers(StorageProxy.java:957)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.cql3.statements.ModificationStatement.executeWithoutCondition(ModificationStatement.java:435)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.cql3.statements.ModificationStatement.execute(ModificationStatement.java:421)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.cql3.QueryProcessor.processStatement(QueryProcessor.java:225)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.cql3.QueryProcessor.processPrepared(QueryProcessor.java:532)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.cql3.QueryProcessor.processPrepared(QueryProcessor.java:509)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.transport.messages.ExecuteMessage.execute(ExecuteMessage.java:146)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.transport.Message$Dispatcher.processRequest(Message.java:687)
>> [apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.transport.Message$Dispatcher.lambda$channelRead0$0(Message.java:593)
>> [apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
>> ~[na:1.8.0_302]
>> at
>> org.apache.cassandra.concurrent.AbstractLocalAwareExecutorService$FutureTask.run(AbstractLocalAwareExecutorService.java:162)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at
>> org.apache.cassandra.concurrent.SEPWorker.run(SEPWorker.java:113)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_302]
>> Caused by: java.lang.UnsupportedOperationException: null
>> at java.util.AbstractCollection.add(AbstractCollection.java:262)
>> ~[na:1.8.0_302]
>> at MyTrigger.augment(MyTrigger.java:26) ~[na:na]
>> at
>> org.apache.cassandra.triggers.TriggerExecutor.executeInternal(TriggerExecutor.java:234)
>> ~[apache-cassandra-3.11.11.jar:3.11.11]
>> ... 14 common frames omitted
>> ```
>>
>> I guess I made a mistake in my trigger implementation.
>> Not sure if it is the correct way to do that.
>>
>> Could you give me some advice?
>>
>> Thank you.
>>
>
