How to query struct array with Hive (get_json_object) or json serde

DatWunGuy102 picture DatWunGuy102 · Jul 10, 2017 · Viewed 30.5k times · Source

I am trying to query the following JSON example file stored on my HDFS

{
    "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"
                            }
                        }
                    }
                ]
            }
        ]
    }
}

I used the following to create an external table over the data

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';

Ideally, I want to query the data such that it would return to me as such:

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

Can someone provide me an example of how I can query without writing it in the following manner:

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

Most importantly, I would like to not define the array item element number. In my example, I am only able to target the first element of my array (tag4_1_1_1). I would to target everything if possible.

Answer

DatWunGuy102 picture DatWunGuy102 · Jul 11, 2017

Found a really good blog at: 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

I'm very satisfied, but I want to check out the json tuple and see how it performs versus the "get_json_object" class