将字段由 \ 分隔的嵌套 json 存储在 hive 外部表中

编程问答 2022-06-01

问题描述

我嵌套了 JSON，其字段由 \ 分隔，同时将该 json 保存到 hive 外部表，然后出现错误。

{"value":"{\"DUUID\": 67,\"GUUID\": 514,\"EOT\": 219.0,\"cc\": 3,\"enghr\": 20.0,\"battvolt\": 0.0,\"EOP\": 120.0,\"ts\": \"2020-12-31T14:22:37\",\"ts1\": 1609404757.2771647}"}

以上是我的json消息，存放在hdfs /lambda3/test目录

我在 hive 中编写了如下查询 ---

> CREATE EXTERNAL TABLE demo1.json11(
> value struct<
>
>     DUUID: INTEGER,>     GUUID :INTEGER,>     EOT: Double,>     cc :Double,>     enghr :double,>     battvolt : double,>     EOP : double,>     ts : timestamp,>     ts1 : timestamp >
> )
> ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe'
> LOCATION 'hdfs://localhost:9000/lambda3/test/';

然后当我发出命令 select * from json11 然后我收到如下错误消息

Exception in thread "main" java.lang.Error: Data is not JSONObject  but java.lang.String with value {"DUUID": 67,"GUUID": 514,"EOT": 219.0,"cc": 3,"enghr": 20.0,"battvolt": 0.0,"EOP": 120.0,"ts": "2020-12-31T14:22:37","ts1": 1609404757.2771647}
        at org.openx.data.jsonserde.objectinspector.JsonStructObjectInspector.getStructFieldData(JsonStructObjectInspector.java:73)
        at org.apache.hadoop.hive.serde2.SerDeUtils.buildJSONString(SerDeUtils.java:366)
        at org.apache.hadoop.hive.serde2.SerDeUtils.getJSONString(SerDeUtils.java:202)
        at org.apache.hadoop.hive.serde2.DelimitedJSONSerDe.serializefield(DelimitedJSONSerDe.java:61)
        at org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe.doSerialize(LazySimpleSerDe.java:231)
        at org.apache.hadoop.hive.serde2.AbstractEncodingAwareSerDe.serialize(AbstractEncodingAwareSerDe.java:55)
        at org.apache.hadoop.hive.serde2.DefaultFetchFormatter.convert(DefaultFetchFormatter.java:67)
        at org.apache.hadoop.hive.serde2.DefaultFetchFormatter.convert(DefaultFetchFormatter.java:36)
        at org.apache.hadoop.hive.ql.exec.ListSinkOperator.process(ListSinkOperator.java:94)
        at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:897)
        at org.apache.hadoop.hive.ql.exec.SelectOperator.process(SelectOperator.java:95)
        at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:897)
        at org.apache.hadoop.hive.ql.exec.TableScanoperator.process(TableScanoperator.java:130)
        at org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:438)
        at org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:430)
        at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:147)
        at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:2208)
        at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:253)
        at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:184)
        at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:403)
        at org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:821)
        at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:759)
        at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:686)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.hadoop.util.RunJar.run(RunJar.java:226)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:141)

请告诉我如何将这些 JSON 存储到 Hive 表。 提前致谢

解决方法

您的 JSON“值”是一个包含 JSON {"value":string} 的字符串，而不是嵌套的 JSON 结构。 嵌套的 JSON 结构应如下所示：

{"value": {"DUUID": 67,"GUUID": 514,"EOT": 219.0,"cc": 3,"enghr": 20.0,"battvolt": 0.0,"EOP": 120.0,"ts": "2020-12-31T14:22:37","ts1": 1609404757.2771647}}

如果无法修复 JSON，则创建值为 STRING 的表并使用 json_tuple 解析它：

CREATE EXTERNAL TABLE demo1.json11(
value string 
) 
ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe' 
LOCATION 'hdfs://localhost:9000/lambda3/test/';


select DUUID,GUUID,EOT,cc,enghr,battvolt,EOP,ts,ts1
  from demo1.json11 j
       lateral view json_tuple (j.value,'DUUID','GUUID','EOT','cc','enghr','battvolt','EOP','ts','ts1') e 
                           as DUUID,ts1

必要时转换类型，如下所示：

CAST(DUUID as int) as DUUID,...
CAST(ts as timestamp) as ts,CAST(ts1as timestamp) as ts1
create-tablehdfshivehiveqljson