Exclusive-Startschlüssel kann nicht auf DynamoDB gesetzt werden

Question

Ich versuche, den exklusiven Startschlüssel für meine Anfrage zu setzen, damit ich meinen LastEvaluatedKey später haben kann.

Die folgende Ausnahme tritt auf, wenn ich über meine Abfrageergebnisse iteriere. Kann mir jemand diesbezüglich helfen?

„Die bereitgestellten Starttaste entspricht nicht den Bereich Schlüssel Prädikat“

QuerySpec queryExpression = ...  
queryExpression = queryExpression.withExclusiveStartKey(OFFSET_PRIMARY_KEY, offsetParts[OFFSET_PRIMARY_KEY_INDEX], OFFSET_SORT_KEY, Long.valueOf(offsetParts[OFFSET_SORT_KEY_INDEX])); 
ItemCollection<QueryOutcome> items = table.query(queryExpression); 

Iterator<Item> iterator = items.iterator(); 

iterator.forEachRemaining(m -> { //exception occurs here 
           ... 
          }); 

Stack Trace:

com.amazonaws.AmazonServiceException: The provided starting key does not match the range key predicate (Service: AmazonDynamoDBv2; Status Code: 400; Error Code: ValidationException; Request ID: 6EA9NOO079F7VUVV1JP92P05MRVV4KQNSO5AEMVJF66Q9ASUAAJG) 
    at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:1389) 
    at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:902) 
    at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:607) 
    at com.amazonaws.http.AmazonHttpClient.doExecute(AmazonHttpClient.java:376) 
    at com.amazonaws.http.AmazonHttpClient.executeWithTimer(AmazonHttpClient.java:338) 
    at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:287) 
    at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.invoke(AmazonDynamoDBClient.java:1985) 
    at com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient.query(AmazonDynamoDBClient.java:1620) 
    at com.amazonaws.services.dynamodbv2.document.internal.QueryCollection.firstPage(QueryCollection.java:53) 
    at com.amazonaws.services.dynamodbv2.document.internal.PageIterator.next(PageIterator.java:45) 
    at com.amazonaws.services.dynamodbv2.document.internal.PageIterator.next(PageIterator.java:25) 
    at java.lang.Iterable.forEach(Iterable.java:74) 
    at com.my.com.services.database.DynamoDatabaseRepository.fetchMessageList(DynamoDatabaseRepository.java:675) 
    at service.DatabaseServiceTest.accc(DatabaseServiceTest.java:106) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) 
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) 
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) 
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) 
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) 
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) 
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) 
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) 
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) 
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) 
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) 
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363) 
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137) 
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:78) 
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:212) 
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:68) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at com.intellij.rt.execution.CommandLineWrapper.main(CommandLineWrapper.java:130) 

Answer 1

Dies kann passieren, wenn die Zeile durch die ExclusiveStartKey dargestellt, die Sie vorbei nicht mehr erscheint im Dynamodb-Abfrageergebnis.

Betrachten wir den Fall unter:

 
Your Primary partition key is named "message_id" 
Your Primary sort key is named "message_timestamp" 
Your ExclusiveStartKey value is: '{"message_id":"3483b80a358cf60decfccc329bd5e72e","message_timestamp":1481114525}' 
You are using KeyConditionExpression as: Key("message_id").eq("3483b80a358cf60decfccc329bd5e72e") & Key("message_timestamp").gt(1481202107) 

Since the message_timestamp in KeyConditionExpression is greater than the corresponding value in ExclusiveStartKey, dynamodb will throw the error that you mentioned.