Spark：联合只能在具有兼容列类型的表上执行。Struct<名称，ID>！=Struct<ID，名称>

错误：只能对具有兼容列类型的表执行联合。 struct（tier：string，skyward_number：string，skyward_points：string）<> struct（skyward_number：string，tier：string，skyward_points：string）在第二个表的第一列；

此处struct字段的顺序不同，但其余部分都相同。

dataframe1架构

root
 |-- emcg_uuid: string (nullable = true)
 |-- name: string (nullable = true)
 |-- phone_no: string (nullable = true)
 |-- dob: string (nullable = true)
 |-- country: string (nullable = true)
 |-- travel_type: string (nullable = true)
 |-- gdpr_restricted_flg: string (nullable = false)
 |-- gdpr_reason_code: string (nullable = false)
 |-- document: map (nullable = true)
 |    |-- key: string
 |    |-- value: string (valueCOntainsNull= true)
 |-- skyward: struct (nullable = false)
 |    |-- tier: string (nullable = false)
 |    |-- skyward_number: string (nullable = false)
 |    |-- skyward_points: string (nullable = false)

dataframe2 schema
root
 |-- emcg_uuid: string (nullable = true)
 |-- name: string (nullable = true)
 |-- phone_no: string (nullable = true)
 |-- dob: string (nullable = true)
 |-- country: string (nullable = true)
 |-- travel_type: string (nullable = true)
 |-- gdpr_restricted_flg: string (nullable = true)
 |-- gdpr_reason_code: string (nullable = true)
 |-- document: map (nullable = true)
 |    |-- key: string
 |    |-- value: string (valueCOntainsNull= true)
 |-- skyward: struct (nullable = false)
 |    |-- skyward_number: string (nullable = false)
 |    |-- tier: string (nullable = false)
 |    |-- skyward_points: string (nullable = false)

如何解决呢？