Neo4j从Java嵌入式在线备份

Question

我在项目中使用Neo4j（嵌入式）企业版1.9.4以及Scala-Neo4j包装器。我尝试使用下面的Java备份Neo4j数据

def backup_data() 
    { 
     val backupPath: File = new File("D:/neo4j-enterprise-1.9.4/data/backup/") 
     val backup = OnlineBackup.from("127.0.0.1") 
     if(backupPath.list().length > 0) 
     { 
      backup.incremental(backupPath.getPath()) 
     } 
     else 
     { 
     backup.full(backupPath.getPath()); 
     } 
    } 

它对于完全备份工作正常。但增量备份部分正在抛出Null指针异常。

我哪里错了？

编辑

通过斯卡拉-的Neo4j包装构建图数据库实例

class MyNeo4jClass extends SomethingClass with Neo4jWrapper with EmbeddedGraphDatabaseServiceProvider { 
    def neo4jStoreDir = "/tmp/temp-neo-test" 
    . . . 
} 

堆栈跟踪

Exception in thread "main" java.lang.NullPointerException 
    at org.neo4j.consistency.checking.OwnerChain$3.checkReference(OwnerChain.java:111) 
    at org.neo4j.consistency.checking.OwnerChain$3.checkReference(OwnerChain.java:106) 
    at org.neo4j.consistency.report.ConsistencyReporter$DiffReportHandler.checkReference(ConsistencyReporter.java:330) 
    at org.neo4j.consistency.report.ConsistencyReporter.dispatchReference(ConsistencyReporter.java:109) 
    at org.neo4j.consistency.report.PendingReferenceCheck.checkReference(PendingReferenceCheck.java:50) 
    at org.neo4j.consistency.store.DirectRecordReference.dispatch(DirectRecordReference.java:39) 
    at org.neo4j.consistency.report.ConsistencyReporter$ReportInvocationHandler.forReference(ConsistencyReporter.java:236) 
    at org.neo4j.consistency.report.ConsistencyReporter$ReportInvocationHandler.dispatchForReference(ConsistencyReporter.java:228) 
    at org.neo4j.consistency.report.ConsistencyReporter$ReportInvocationHandler.invoke(ConsistencyReporter.java:192) 
    at $Proxy17.forReference(Unknown Source) 
    at org.neo4j.consistency.checking.OwnerChain.check(OwnerChain.java:143) 
    at org.neo4j.consistency.checking.PropertyRecordCheck.checkChange(PropertyRecordCheck.java:57) 
    at org.neo4j.consistency.checking.PropertyRecordCheck.checkChange(PropertyRecordCheck.java:35) 
    at org.neo4j.consistency.report.ConsistencyReporter.dispatchChange(ConsistencyReporter.java:101) 
    at org.neo4j.consistency.report.ConsistencyReporter.forPropertyChange(ConsistencyReporter.java:382) 
    at org.neo4j.consistency.checking.incremental.StoreProcessor.checkProperty(StoreProcessor.java:61) 
    at org.neo4j.consistency.checking.AbstractStoreProcessor.processProperty(AbstractStoreProcessor.java:95) 
    at org.neo4j.consistency.store.DiffRecordStore$DispatchProcessor.processProperty(DiffRecordStore.java:207) 
    at org.neo4j.kernel.impl.nioneo.store.PropertyStore.accept(PropertyStore.java:83) 
    at org.neo4j.kernel.impl.nioneo.store.PropertyStore.accept(PropertyStore.java:43) 
    at org.neo4j.consistency.store.DiffRecordStore.accept(DiffRecordStore.java:159) 
    at org.neo4j.kernel.impl.nioneo.store.RecordStore$Processor.applyById(RecordStore.java:180) 
    at org.neo4j.consistency.store.DiffStore.apply(DiffStore.java:73) 
    at org.neo4j.kernel.impl.nioneo.store.StoreAccess.applyToAll(StoreAccess.java:174) 
    at org.neo4j.consistency.checking.incremental.IncrementalDiffCheck.execute(IncrementalDiffCheck.java:43) 
    at org.neo4j.consistency.checking.incremental.DiffCheck.check(DiffCheck.java:39) 
    at org.neo4j.consistency.checking.incremental.intercept.CheckingTransactionInterceptor.complete(CheckingTransactionInterceptor.java:160) 
    at org.neo4j.kernel.impl.transaction.xaframework.InterceptingXaLogicalLog$1.intercept(InterceptingXaLogicalLog.java:79) 
    at org.neo4j.kernel.impl.transaction.xaframework.XaLogicalLog$LogDeserializer.readAndWriteAndApplyEntry(XaLogicalLog.java:1120) 
    at org.neo4j.kernel.impl.transaction.xaframework.XaLogicalLog.applyTransaction(XaLogicalLog.java:1292) 
    at org.neo4j.kernel.impl.transaction.xaframework.XaResourceManager.applyCommittedTransaction(XaResourceManager.java:766) 
    at org.neo4j.kernel.impl.transaction.xaframework.XaDataSource.applyCommittedTransaction(XaDataSource.java:246) 
    at org.neo4j.com.ServerUtil.applyReceivedTransactions(ServerUtil.java:423) 
    at org.neo4j.backup.BackupService.unpackResponse(BackupService.java:453) 
    at org.neo4j.backup.BackupService.incrementalWithContext(BackupService.java:388) 
    at org.neo4j.backup.BackupService.doIncrementalBackup(BackupService.java:286) 
    at org.neo4j.backup.BackupService.doIncrementalBackup(BackupService.java:273) 
    at org.neo4j.backup.OnlineBackup.incremental(OnlineBackup.java:147) 
    at Saddahaq.User_node$.backup_data(User_node.scala:1637) 
    at Saddahaq.User_node$.main(User_node.scala:2461) 
    at Saddahaq.User_node.main(User_node.scala) 

Answer 1

备份照片之后，备份目标检查为consiste NCY。一致性检查器的增量版本目前存在导致观察到的NPE的错误。

解决方法：要么始终以全备份与backup.full或防止使用NPE的

backup.incremental(backupPath.getPath(), false);