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DNodeException: Cannot execute modification statement



The DNode or Adaptive logic is working fine on development environment with single node.

The same code is not working in pre-prod multi-node environment.

The error message coming on few nodes at same time it is working fine on other nodes and it sporadic in nature.

Error Messages

Caused by: com.pega.dsm.dnode.impl.core.ExceptionWithInputRecord: com.pega.dsm.dnode.api.DNodeException: Cannot execute modification statement
... 86 more
Caused by: com.pega.dsm.dnode.api.DNodeException: Cannot execute modification statement
at com.pega.dsm.dnode.impl.cassandra.CassandraDao.executeStatement(
at com.pega.dsm.dnode.impl.cassandra.CassandraDataRepository.insert(
at com.pega.dsm.dnode.impl.dataset.cassandra.CassandraSaveOperation$2.emit(
at com.pega.dsm.dnode.impl.dataflow.strategy.DelayedLearning.saveResultsForDelayedLearning(
at com.pega.dsm.dnode.impl.dataflow.strategy.StrategyStageProcessor.onNext(
... 85 more
Caused by: org.apache.cassandra.exceptions.UnavailableException: Cannot achieve consistency level ONE
at org.apache.cassandra.db.ConsistencyLevel.assureSufficientLiveNodes(
at org.apache.cassandra.service.AbstractWriteResponseHandler.assureSufficientLiveNodes(
at org.apache.cassandra.service.StorageProxy.performWrite(
at org.apache.cassandra.service.StorageProxy.mutate(
at org.apache.cassandra.cql3.statements.ModificationStatement.execute(
at com.pega.dsm.dnode.impl.cassandra.CassandraDao.executeStatement(

Steps to Reproduce

1) Execute SOAP Service.
2) In Service Activity - setup predictors.
3) Execute Data Flow which in turn calls Strategies which contain Adaptive Model.

Root Cause

A defect in Pegasystems’ code or rules.


Apply HFix-28748.


Published August 24, 2016 - Updated October 8, 2020

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