在 hive 外部表中存储嵌套的 json，其字段由 \ 分隔

Posted 2023-03-23

【中文标题】在 hive 外部表中存储嵌套的 json，其字段由 \\ 分隔

【英文标题】：store nested json whose fields are seperated by \ in hive external table在 hive 外部表中存储嵌套的 json，其字段由 \ 分隔

【发布时间】：2020-12-31 11:38:18

【问题描述】：

我嵌套了 JSON，其字段由 \ 分隔，同时将该 json 保存到配置单元外部表，然后我收到错误。

"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 目录中

我在蜂巢中写了如下查询---

> 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/';

然后当我发出命令时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 表中。 提前谢谢你

【问题讨论】：

"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" 这是有效载荷结构

您的有效负载不是嵌套的 JSON - 它具有字符串形式的值。您需要处理该值，使其成为真正的 json，而不是字符串。

【参考方案1】：

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 对其进行解析：

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, GUUID,EOT,cc,enghr,battvolt,EOP,ts,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