Why DynamoDB java sdk doesn't allow always auto-generated keys? -

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i'd implement change history objects in dynamodb. easy way of doing specify "object id" hash , "updated time" range key. however, java sdk doesn't allow annotating keys autogenerated (changing value without annotation convenience seems work). why?

example code:

@dynamodbtable(tablename = "data") public class person {      public static void main(string[] args) {         amazondynamodbclient client = new amazondynamodbclient()                 .withendpoint("http://localhost:8000");         dynamodbmapper mapper = new dynamodbmapper(client);          tableutils.deletetableifexists(client, mapper.generatedeletetablerequest(person.class));         tableutils.createtableifnotexists(client, mapper.generatecreatetablerequest(person.class)                 .withprovisionedthroughput(new provisionedthroughput(1l, 1l))         );          person person = new person();         person.setpersonid("abc");          mapper.save(person);         mapper.save(person);          tableutils.deletetableifexists(client, mapper.generatedeletetablerequest(person.class));     }      @dynamodbhashkey     private string personid;      @dynamodbrangekey     @dynamodbautogeneratedtimestamp     private long updated;      public string getpersonid() {         return personid;     }      public void setpersonid(string personid) {         this.personid = personid;     }      public long getupdated() {         return updated;     }      public void setupdated(long updated) {         this.updated = updated;     } }

exception:

exception in thread "main" com.amazonaws.services.dynamodbv2.datamodeling.dynamodbmappingexception: field com.dynamodb.testpackage.person[updated] must not have auto-generated key strategy     @ com.amazonaws.services.dynamodbv2.datamodeling.dynamodbmapperfieldmodel$builder.build(dynamodbmapperfieldmodel.java:797)     @ com.amazonaws.services.dynamodbv2.datamodeling.standardmodelfactories$schemafactory.newtablemodel(standardmodelfactories.java:118)     @ com.amazonaws.services.dynamodbv2.datamodeling.standardmodelfactories$schemafactory.gettablemodel(standardmodelfactories.java:86)     @ com.amazonaws.services.dynamodbv2.datamodeling.dynamodbmapper.gettablemodel(dynamodbmapper.java:401)     @ com.amazonaws.services.dynamodbv2.datamodeling.dynamodbmapper.generatecreatetablerequest(dynamodbmapper.java:2432)     @ com.dynamodb.testpackage.person.main(person.java:21)     @ sun.reflect.nativemethodaccessorimpl.invoke0(native method)     @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:62)     @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:43)     @ java.lang.reflect.method.invoke(method.java:497)     @ com.intellij.rt.execution.application.appmain.main(appmain.java:147)

your use-case atypical. don't want hash , range key of object change. in fact go far it's discouraged.

in fact, dynamodb item uniquely characterized it's key (whether partition key only, or partition + range keys together) changing range key creates new item technically not update.

i'm not sure if accurately represents the reason why mixing @dynamodbautogeneratedtimestamp , @dynamodbrangekey not supported in sdk it's reason.


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