hive 无法使用嵌套的 avro 架构创建表

Question

我正在尝试使用嵌套的 avro 架构来创建配置单元表。但它不起作用。我在 cdh5.7.2 中使用 hive 1.1。

这是我的嵌套 avro 架构：

[
    {
        "type": "record",
        "name": "Id",
        "namespace": "com.test.app_list",
        "doc": "Device ID",
        "fields": [
            {
                "name": "idType",
                "type": "int"
            },{
                "name": "id",
                "type": "string"
            }
        ]
    },

    {
        "type": "record",
        "name": "AppList",
        "namespace": "com.test.app_list",
        "doc": "",
        "fields": [
            {
                "name": "appId",
                "type": "string",
                "avro.java.string": "String"
            },
            {
                "name": "timestamp",
                "type":  "long"
            },

            {
                "name": "idList",
                "type": [{"type": "array", "items": "com.test.app_list.Id"}]
            }

        ]
    }
]

还有我创建表的sql：

CREATE EXTERNAL TABLE app_list
ROW FORMAT SERDE
'org.apache.hadoop.hive.serde2.avro.AvroSerDe'
STORED AS INPUTFORMAT
'org.apache.hadoop.hive.ql.io.avro.AvroContainerInputFormat'
OUTPUTFORMAT
'org.apache.hadoop.hive.ql.io.avro.AvroContainerOutputFormat'
TBLPROPERTIES (
'avro.schema.url'='/hive/schema/test_app_list.avsc');

但是蜂巢给了我：

FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. java.lang.RuntimeException: MetaException(message:org.apache.hadoop.hive.serde2.avro.AvroSerdeException Schema for table must be of type RECORD. Received type: UNION)

hive 文档显示：Supports arbitrarily nested schemas. 来自：https://cwiki.apache.org/confluence/display/Hive/AvroSerDe#AvroSerDe-Overview–WorkingwithAvrofromHive

数据样本：

{
    "appId":{"string":"com.test.app"},
    "timestamp":{"long":1495893601606},
    "idList":{
        "array":[
            {"idType":15,"id":"6c:5c:14:c3:a5:39"},
            {"idType":13,"id":"eb297afe56ff340b6bb7de5c5ab09193"}
        ]
    }

}

但我不知道该怎么做。我需要一些帮助来解决这个问题。谢谢！

Answer 1

您的 avro 架构的顶层期望是记录类型，这就是 Hive 不允许这样做的原因。一种解决方法是创建顶层作为记录，并在内部创建两个字段作为记录类型。

{ 
        "type": "record",
        "name": "myRecord",
        "namespace": "com.test.app_list"
          "fields": [
    {
        "type": "record",
        "name": "Id",
        "doc": "Device ID",
        "fields": [
            {
                "name": "idType",
                "type": "int"
            },{
                "name": "id",
                "type": "string"
            }
        ]
    },

    {
        "type": "record",
        "name": "AppList",
        "doc": "",
        "fields": [
            {
                "name": "appId",
                "type": "string",
                "avro.java.string": "String"
            },
            {
                "name": "timestamp",
                "type":  "long"
            },

            {
                "name": "idList",
                "type": [{"type": "array", "items": "com.test.app_list.Id"}]
            }

        ]
    }
    ]
}