Hazelcast:添加索引时出现问题

问题描述

我有一个hazelcast实例，其键的类型为MyObject，值是一个枚举.假设MyObject类的属性之一是date，其类型为java.sql.Date.

I have a hazelcast instance whose key is of type MyObject and value is an enum.Let's say one of the attributes of MyObject class is date which is of type java.sql.Date.

    class MyObject {
       private Date date;
       public Date getDate() {
         return date;
       }
       public void setDate(Date date) {
         this.date = date
       }
    }

public enum MyEnum {
  TEST_ENUM;
}

我还使用谓词对键进行过滤以检索枚举值.例如:

Also I am using predicate to filter on the keys retrieve the enum value.For ex:

EntryObject entryObject = new PredicateBuilder().getEntryObject();
PredicateBuiler predicateBuilder = entryObject.key.get(date).isNull;

这是我尝试添加索引的方式:

This is how I am trying to add index:

IMap<MyObject, MyEnum> map = hazelcastInstance.getMap("test");
map.addIndex("date", true)

但是一旦执行，就会引发异常:

But as soon as this gets executed an exception is being thrown:

com.hazelcast.query.QueryException: java.lang.IllegalArgumentException: There is no suitable accessor for 'date' on class 'class com.main.constants.myEnum'
at com.hazelcast.query.impl.getters.ReflectionHelper.createGetter(ReflectionHelper.java:176)
at com.hazelcast.query.impl.getters.Extractors.instantiateGetter(Extractors.java:88)
at com.hazelcast.query.impl.getters.Extractors.getGetter(Extractors.java:73)
at com.hazelcast.query.impl.getters.Extractors.extract(Extractors.java:57)
at com.hazelcast.query.impl.QueryableEntry.extractAttributeValueFromTargetObject(QueryableEntry.java:156)
at com.hazelcast.query.impl.QueryableEntry.extractAttributeValue(QueryableEntry.java:82)
at com.hazelcast.query.impl.QueryableEntry.getAttributeValue(QueryableEntry.java:48)
at com.hazelcast.query.impl.QueryableEntry.getConverter(QueryableEntry.java:67)
at com.hazelcast.query.impl.IndexImpl.saveEntryIndex(IndexImpl.java:67)
at com.hazelcast.map.impl.operation.AddIndexOperation.run(AddIndexOperation.java:75)

我了解它正在尝试在值类中找到索引属性

I understand it's trying to find the index attribute in the value class

如何使此功能正常工作，即在键上而不是在值上添加索引.

How do I get this thing working i.e. add the index on the Key rather than on the value.

推荐答案

在编写测试时，我实际上发现了您的问题:-)

While writing a test I actually found your problem :-)

import com.hazelcast.core.Hazelcast;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.IMap;
import com.hazelcast.query.EntryObject;
import com.hazelcast.query.PredicateBuilder;

import java.io.Serializable;
import java.sql.Date;

public class Test
{
    public static void main(String[] args)
    {
        HazelcastInstance hz = Hazelcast.newHazelcastInstance();

        IMap<MyObject, MyEnum> map = hz.getMap("test");

        EntryObject entryObject = new PredicateBuilder().getEntryObject();
        PredicateBuilder builder = entryObject.key().get("date").isNull();

        map.addIndex("__key#date", true);

        map.put(new MyObject(), MyEnum.TEST_ENUM);
    }

    public static class MyObject implements Serializable
    {
        private Date date;

        public Date getDate()
        {
            return date;
        }

        public void setDate(Date date)
        {
            this.date = date;
        }
    }

    public static enum MyEnum {
        TEST_ENUM;
    }
}

诀窍是基于map键而不是默认值创建索引.您已经在查询entryObject.key()中进行了此操作，但是在索引定义__key.date中未进行此操作.

The trick is to create the index based on the map-key and not the value which is taken by default. You already did it in your query entryObject.key() but missed it on the index definition __key.date.

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