从AVSC创建Hive表，该表包含对以前定义的模式作为类型的引用

Question

我希望找到一种通过Hive获取以下AVSC文件内容的方法，并将嵌套模式"RENTALRECORDTYPE“外部化，以实现模式重用。

{
    "type": "record",
    "name": "EMPLOYEE",
    "namespace": "",
    "doc": "EMPLOYEE is a person that works here",
    "fields": [
        {
            "name": "RENTALRECORD",
            "type": {
                "type": "record",
                "name": "RENTALRECORDTYPE",
                "namespace": "",
                "doc": "Rental record is a record that is kept on every item rented",
                "fields": [
                    {
                        "name": "due_date",
                        "doc": "The date when item is due",
                        "type": "int"
                    } 
                ]
            }
        },
        {
            "name": "hire_date",
            "doc": "Employee date of hire",
            "type": "int"
        }
    ]
}

这种定义模式的方法工作得很好。我能够发出以下HiveQL语句，并成功地创建了该表。

CREATE EXTERNAL TABLE employee
STORED AS AVRO
LOCATION '/user/dtom/store/data/employee'
TBLPROPERTIES ('avro.schema.url'='/user/dtom/store/schema/employee.avsc');

但是，我希望能够引用现有模式，而不是重复多个模式中的记录定义。例如，将生成两个AVSC文件，而不是单个模式文件。即rentalrecord.avsc和employee.avsc。

rentalrecord.avsc

{
    "type": "record",
    "name": "RENTALRECORD",
    "namespace": "",
    "doc": "A record that is kept for every rental",
    "fields": [
        {
            "name": "due_date",
            "doc": "The date on which the rental is due back to the store",
            "type": "int"
        }
    ]
}

employee.avsc

{
    "type": "record",
    "name": "EMPLOYEE",
    "namespace": "",
    "doc": "EMPLOYEE is a person that works for the VIDEO STORE",
    "fields": [
        {
            "name": "rentalrecord",
            "doc": "A rental record is a record on every rental",
            "type": "RENTALRECORD"
        },
        {
            "name": "hire_date",
            "doc": "Employee date of hire",
            "type": "int"
        }
    ]
}

在上述场景中，我们希望能够将employee.avsc RENTALRECORD模式定义外部化，并能够在employee.avsc和其他地方重用它。

当试图使用以下两条HiveQL语句导入架构时，它会失败…

CREATE EXTERNAL TABLE rentalrecord
STORED AS AVRO
LOCATION '/user/dtom/store/data/rentalrecord'
TBLPROPERTIES ('avro.schema.url'='/user/dtom/store/schema /rentalrecord.avsc');

CREATE EXTERNAL TABLE employee
STORED AS AVRO
LOCATION '/user/dtom/store/data/employee'
TBLPROPERTIES ('avro.schema.url'='/user/dtom/store/schema/employee.avsc');

rentalrecord.avsc已成功导入，但employee.avsc在第一个字段定义上失败。类型“RENTALRECORD”的字段。以下错误由Hive…输出

失败:执行错误，从org.apache.hadoop.hive.ql.exec.DDLTask返回代码1。MetaException(message:org.apache.hadoop.hive.serde2.SerDeException遇到了异常确定模式。返回指示问题的信号架构："RENTALRECORD“不是定义的名称。"rentalrecord“字段的类型必须是已定义的名称或{" type "：.}表达式。

我的研究告诉我，Avro文件确实支持这种模式恢复形式。所以要么我遗漏了一些东西，要么这是一些不被蜂巢所支持的东西。

任何帮助都将不胜感激。

Answer 1

我定义了一个包含所有引用的AVDL，然后使用带有idl2schemata选项的avro文件来生成avsc。生成的avsc就像一个魅力的蜂巢！