如何将重复结构字段从一列简化为另一列

我在表中有一个数组字段,格式如下(从数据存储导出):

point   RECORD  REPEATED
point.x FLOAT   NULLABLE
point.y FLOAT   NULLABLE
point.key   RECORD  NULLABLE    
point.key.namespace STRING  NULLABLE    
point.key.app   STRING  NULLABLE    
point.key.path  STRING  NULLABLE    
point.key.kind  STRING  NULLABLE    
point.key.name  STRING  NULLABLE    
point.key.id    INTEGER NULLABLE

我想将此字段从表复制到另一个表,但格式要简化。我只需要保留点.x和点.y:

point   RECORD  REPEATED
point.x FLOAT   NULLABLE
point.y FLOAT   NULLABLE