问题
I have a hive table to load JSON data. There are two values in my JSON. Both have data type as string. If I keep them as bigint, then select on this table gives below error:
Failed with exception java.io.IOException:org.apache.hadoop.hive.serde2.SerDeException: org.codehaus.jackson.JsonParseException: Current token (VALUE_STRING) not numeric, can not use numeric value accessors
at [Source: java.io.ByteArrayInputStream@3b6c740b; line: 1, column: 21]
If I change it two string, then it works OK.
Now, because these columns are in string, I am not able to use from_unixtime method for these columns.
If I try to alter these columns data types from string to bigint, I get below error:
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. Unable to alter table. The following columns have types incompatible with the existing columns in their respective positions : uploadtimestamp
Below is my create table statement:
create table ABC
(
uploadTimeStamp bigint
,PDID string
,data array
<
struct
<
Data:struct
<
unit:string
,value:string
,heading:string
,loc:string
,loc1:string
,loc2:string
,loc3:string
,speed:string
,xvalue:string
,yvalue:string
,zvalue:string
>
,Event:string
,PDID:string
,`Timestamp`:string
,Timezone:string
,Version:string
,pii:struct<dummy:string>
>
>
)
row format serde 'org.apache.hive.hcatalog.data.JsonSerDe'
stored as textfile;
My JSON:
{"uploadTimeStamp":"1488793268598","PDID":"123","data":[{"Data":{"unit":"rpm","value":"100"},"EventID":"E1","PDID":"123","Timestamp":1488793268598,"Timezone":330,"Version":"1.0","pii":{}},{"Data":{"heading":"N","loc":"false","loc1":"16.032425","loc2":"80.770587","loc3":"false","speed":"10"},"EventID":"Location","PDID":"skga06031430gedvcl1pdid2367","Timestamp":1488793268598,"Timezone":330,"Version":"1.1","pii":{}},{"Data":{"xvalue":"1.1","yvalue":"1.2","zvalue":"2.2"},"EventID":"AccelerometerInfo","PDID":"skga06031430gedvcl1pdid2367","Timestamp":1488793268598,"Timezone":330,"Version":"1.0","pii":{}},{"EventID":"FuelLevel","Data":{"value":"50","unit":"percentage"},"Version":"1.0","Timestamp":1488793268598,"PDID":"skga06031430gedvcl1pdid2367","Timezone":330},{"Data":{"unit":"kmph","value":"70"},"EventID":"VehicleSpeed","PDID":"skga06031430gedvcl1pdid2367","Timestamp":1488793268598,"Timezone":330,"Version":"1.0","pii":{}}]}
Any ways I can convert this string unixtimestamp to standard time or I can work with bigint for these columns?
回答1:
If you are talking about Timestamp and Timezone then you can define them as int/big int types.
If you'll look on their definition you'll see that there are no qualifiers (") around the values, therefore they are of numeric types within in the JSON doc:"Timestamp":1488793268598,"Timezone":330
create external table myjson
(
uploadTimeStamp string
,PDID string
,data array
<
struct
<
Data:struct
<
unit:string
,value:string
,heading:string
,loc3:string
,loc:string
,loc1:string
,loc4:string
,speed:string
,x:string
,y:string
,z:string
>
,EventID:string
,PDID:string
,`Timestamp`:bigint
,Timezone:smallint
,Version:string
,pii:struct<dummy:string>
>
>
)
row format serde 'org.apache.hive.hcatalog.data.JsonSerDe'
stored as textfile
location '/tmp/myjson'
;
+------------------------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| myjson.uploadtimestamp | myjson.pdid | myjson.data |
+------------------------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 1486631318873 | 123 | [{"data":{"unit":"rpm","value":"0","heading":null,"loc3":null,"loc":null,"loc1":null,"loc4":null,"speed":null,"x":null,"y":null,"z":null},"eventid":"E1","pdid":"123","timestamp":1486631318873,"timezone":330,"version":"1.0","pii":{"dummy":null}},{"data":{"unit":null,"value":null,"heading":"N","loc3":"false","loc":"14.022425","loc1":"78.760587","loc4":"false","speed":"10","x":null,"y":null,"z":null},"eventid":"E2","pdid":"123","timestamp":1486631318873,"timezone":330,"version":"1.1","pii":{"dummy":null}},{"data":{"unit":null,"value":null,"heading":null,"loc3":null,"loc":null,"loc1":null,"loc4":null,"speed":null,"x":"1.1","y":"1.2","z":"2.2"},"eventid":"E3","pdid":"123","timestamp":1486631318873,"timezone":330,"version":"1.0","pii":{"dummy":null}},{"data":{"unit":"percentage","value":"50","heading":null,"loc3":null,"loc":null,"loc1":null,"loc4":null,"speed":null,"x":null,"y":null,"z":null},"eventid":"E4","pdid":"123","timestamp":1486631318873,"timezone":330,"version":"1.0","pii":null},{"data":{"unit":"kmph","value":"70","heading":null,"loc3":null,"loc":null,"loc1":null,"loc4":null,"speed":null,"x":null,"y":null,"z":null},"eventid":"E5","pdid":"123","timestamp":1486631318873,"timezone":330,"version":"1.0","pii":{"dummy":null}}] |
+------------------------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
Even if you have defined Timestamp as a string you can still cast it to a bigint before using it in a function that requires a bigint.
cast (`Timestamp` as bigint)
hive> with t as (select '0' as `timestamp`) select from_unixtime(`timestamp`) from t;
FAILED: SemanticException [Error 10014]: Line 1:45 Wrong arguments 'timestamp': No matching method for class org.apache.hadoop.hive.ql.udf.UDFFromUnixTime with (string). Possible choices: FUNC(bigint) FUNC(bigint, string) FUNC(int) FUNC(int, string)
hive> with t as (select '0' as `timestamp`) select from_unixtime(cast(`timestamp` as bigint)) from t;
OK
1970-01-01 00:00:00
来源：https://stackoverflow.com/questions/42644561/unable-to-work-with-unixtimestamp-column-type-in-string-data-type