查询DynamoDb全局辅助索引

Question

我正在本地试用dynamodb，并得到了下表：

"Table": {
    "AttributeDefinitions": [
        {
            "AttributeName": "hashKey",
            "AttributeType": "S"
        },
        {
            "AttributeName": "sortKey",
            "AttributeType": "S"
        },
        {
            "AttributeName": "full_json",
            "AttributeType": "S"
        }
    ],
    "TableName": "local",
    "KeySchema": [
        {
            "AttributeName": "hashKey",
            "KeyType": "HASH"
        },
        {
            "AttributeName": "sortKey",
            "KeyType": "RANGE"
        }
    ],
    "TableStatus": "ACTIVE",
    "CreationDateTime": "2021-10-01T15:18:04.413000+02:00",
    "ProvisionedThroughput": {
        "LastIncreaseDateTime": "1970-01-01T01:00:00+01:00",
        "LastDecreaseDateTime": "1970-01-01T01:00:00+01:00",
        "NumberOfDecreasesToday": 0,
        "ReadCapacityUnits": 5,
        "WriteCapacityUnits": 1
    },
    "TableSizeBytes": 1066813,
    "ItemCount": 23,
    "TableArn": "arn:aws:dynamodb:ddblocal:000000000000:table/local",
    "GlobalSecondaryIndexes": [
        {
            "IndexName": "sortKeyIndex",
            "KeySchema": [
                {
                    "AttributeName": "sortKey",
                    "KeyType": "HASH"
                }
            ],
            "Projection": {
                "ProjectionType": "ALL"
            },
            "IndexStatus": "ACTIVE",
            "ProvisionedThroughput": {
                "ReadCapacityUnits": 10,
                "WriteCapacityUnits": 1
            },
            "IndexSizeBytes": 1066813,
            "ItemCount": 23,
            "IndexArn": "arn:aws:dynamodb:ddblocal:000000000000:table/local/index/sortKeyIndex"
        }
    ]
}

我想用这样的Java查询它：

Index index = table.getIndex("sortKeyIndex");
ItemCollection<QueryOutcome> items2 = null;
QuerySpec querySpec = new QuerySpec();
querySpec.withKeyConditionExpression("sortKey > :end_date")
                .withValueMap(new ValueMap().withString(":end_date","2021-06-30T07:49:22.000Z"));
items2 = index.query(querySpec);

但是它抛出了一个异常，“不支持QUery键条件”。我不明白这一点，因为在docs中，"<“操作符被描述为常规操作。有人能帮我吗

Answer 1

DDB 查询()需要一个键条件，其中包括对散列/分区键的相等检查。

您必须提供分区键属性的名称和该属性的单个值。查询返回具有该分区键值的所有项。或者，您可以提供一个排序键属性，并使用比较运算符来细化搜索结果。

换句话说，只有当您有一个复合主键(散列+排序)时，才能真正使用Query()。

如果没有作为表/GSI键的一部分指定的排序键，Query()的作用就像GetItem()使用给定的哈希键返回单个记录一样。