如何使用Hive（get_json_object）或json serde查询结构体数组

Question

我正在尝试查询HDFS上存储的以下JSON示例文件

{
    "tag1": "1.0",
    "tag2": "blah",
    "tag3": "blahblah",
    "tag4": {
        "tag4_1": [{
                "tag4_1_1": [{
                        "tag4_1_1_1": {
                            "Addr": {
                                "Addr1": "blah",
                                "City": "City",
                                "StateProvCd": "NY",
                                "PostalCode": "99999"
                            }
                        }
                        "tag4_1_1_1": {
                            "Addr": {
                                "Addr1": "blah2",
                                "City": "City2",
                                "StateProvCd": "NY",
                                "PostalCode": "99999"
                            }
                        }
                    }
                ]
            }
        ]
    }
}

我使用以下内容在数据上创建了一个外部表

CREATE  EXTERNAL TABLE DB.hv_table
(
  tag1 string
, tag2 string
, tag3 string
, tag4 struct<tag4_1:ARRAY<struct<tag4_1_1:ARRAY<struct<tag4_1_1_1:struct<Addr
                Addr1:string
                , City:string
                , StateProvCd:string
                , PostalCode:string>>>>>>
)
ROW FORMAT SERDE 'org.apache.hive.hcatalog.data.JsonSerDe' 
LOCATION 'HDFS/location';

理想情况下，我想查询数据，以便其返回给我：

select tag1, tag2, tag3, tag4(all data) from DB.hv_table;

有人可以给我提供一个示例，该示例说明如何在不按以下方式编写的情况下进行查询：

select tag1, tag2, tag3
, tag4.tag4_1[0].tag4_1_1[0].tag4_1_1_1.Addr.Addr1 as Addr1 
, tag4.tag4_1[0].tag4_1_1[0].tag4_1_1_1.Addr.City as City 
, tag4.tag4_1[0].tag4_1_1[0].tag4_1_1_1.Addr.StateProvCd as StateProvCd 
, tag4.tag4_1[0].tag4_1_1[0].tag4_1_1_1.Addr.PostalCode as PostalCode 
from DB.hv_table

最重要的是，我不想定义数组项目元素编号。在我的示例中，我只能定位到数组的第一个元素（tag4_1_1_1）。如果可能的话，我会以所有目标为目标。

Answer 1

在以下位置找到了一个非常不错的博客：ThornyDev

CREATE EXTERNAL TABLE IF NOT EXISTS DB.dummyTable (jsonBlob STRING)
LOCATION 'pathOfYourFiles';

SELECT 
get_json_object(jsonBlob, '$.tag1') AS tag1
,get_json_object(jsonBlob, '$.tag2') AS tag2
,get_json_object(jsonBlob, '$.tag3') AS tag3
,get_json_object(jsonBlob, '$.tag4.tag4_1.tag4_1_1.tag4_1_1_1.Addr.Addr1') AS Addr1
,get_json_object(jsonBlob, '$.tag4.tag4_1.tag4_1_1.tag4_1_1_1.Addr.City') AS City
,get_json_object(jsonBlob, '$.tag4.tag4_1.tag4_1_1.tag4_1_1_1.Addr.StateProvCd') AS StateProvCd
,get_json_object(jsonBlob, '$.tag4.tag4_1.tag4_1_1.tag4_1_1_1.Addr.PostalCode') AS PostalCode
FROM DB.dummyTable

我非常满意，但我想查看json元组，并与“ get_json_object”类进行比较，看看其性能如何。