Question

我正在DataNucleus使用HBase。我有一张桌子user。它包含4行。现在我在表格中添加了一个新列。现在，每当我访问没有此列的任何旧user对象时，DataNucleus会尝试使用POJO中的属性映射列，从而引发异常。除了使用虚拟数据更新旧的“用户”对象之外没有其他方法吗？我的对象映射看起来像这样：

@Persistent(columns={@Column(name="next_mail_timestamp", insertValue="#NULL", defaultValue = "#NULL", allowsNull = "true")}, name="nextMailTimestamp", cacheable="false", nullValue=NullValue.DEFAULT)
    private long nextMailTimestamp;

如您所见，我尝试过使用insertValue，defaultValue，allowsNull，nullValue。但似乎没有任何效果。

stacktrace看起来像这样：

at org.apache.hadoop.hbase.util.Bytes.toLong(Bytes.java:479)
    at org.apache.hadoop.hbase.util.Bytes.toLong(Bytes.java:453)
    at org.datanucleus.store.hbase.fieldmanager.FetchFieldManager.fetchLongField(FetchFieldManager.java:269)
    at org.datanucleus.state.AbstractStateManager.replacingLongField(AbstractStateManager.java:2133)
    at com.kuliza.sitepulse.data.User.jdoReplaceField(User.java)
    at com.kuliza.sitepulse.data.User.jdoReplaceFields(User.java)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:1989)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2009)
    at org.datanucleus.store.hbase.query.HBaseQueryUtils$2.fetchFields(HBaseQueryUtils.java:226)
    at org.datanucleus.state.JDOStateManagerImpl.loadFieldValues(JDOStateManagerImpl.java:803)
    at org.datanucleus.state.JDOStateManagerImpl.initialiseForHollow(JDOStateManagerImpl.java:210)
    at org.datanucleus.state.ObjectProviderFactory.newForHollowPopulated(ObjectProviderFactory.java:88)
    at org.datanucleus.ObjectManagerImpl.findObject(ObjectManagerImpl.java:2794)
    at org.datanucleus.store.hbase.query.HBaseQueryUtils.getObjectUsingApplicationIdForResult(HBaseQueryUtils.java:221)
    at org.datanucleus.store.hbase.query.HBaseQueryUtils.getObjectsOfType(HBaseQueryUtils.java:168)
    at org.datanucleus.store.hbase.query.HBaseQueryUtils.getObjectsOfCandidateType(HBaseQueryUtils.java:80)
    at org.datanucleus.store.hbase.query.JDOQLQuery.performExecute(JDOQLQuery.java:271)
    at org.datanucleus.store.query.Query.executeQuery(Query.java:1766)
    at org.datanucleus.store.query.Query.executeWithArray(Query.java:1655)
    at org.datanucleus.store.query.Query.execute(Query.java:1628)
    at org.datanucleus.api.jdo.JDOQuery.execute(JDOQuery.java:221)
    at com.kuliza.sitepulse.service.DataService.getUserWithCredentials(DataService.java:111)
    at com.kuliza.sitepulse.service.AuthenticationService.getUserWithCredentials(AuthenticationService.java:46)
    at com.kuliza.sitepulse.controller.AuthenticationController.signIn(AuthenticationController.java:69)

我的方法是（在DataService.java:111中）（抛出异常）

@Override
    public User getUserWithCredentials(String userName, String password){
        PersistenceManager pm = pmf.getPersistenceManager();
        Query q = pm.newQuery("SELECT FROM " + User.class.getName() + " WHERE userName == \""+userName+"\"" +" && password == " +
                " \""+password + "\"");
        List<User> c = (List<User>)q.execute();
        pm.close();
        if(c.size() > 0)
            return c.get(0);
        else
            return null;
    }

我实际上添加了两个新列（mailIntervalInMilliseconds，nextMailTimestamp），它们都是long，在堆栈跟踪中我看到它试图将db列转换为Long （AFAIK）

Answer 1

DataNucleus HBase插件的发布版本目前不支持所有模式演变模式。特别是当它们是原始类型时添加字段/属性。但是DataNucleus SVN确实支持这一点，所以你可以使用它。

Datanucleus异常向hbase表添加新列

1 个答案: