amazon-redshift - Redshift : Unnest subquery's result on leader is not supported

Question

我尝试在 RedShift 中解析 JSON。

“输入”列中的字符串是:

[{"desc": "How many people does the video contain?", "name": "Number of People", "type": "dropdown", "values": ["", "Only 1", "2-3", "3+"]}, {"desc": "What is the camera position?", "name": "Movement", "type": "dropdown", "values": ["", "Fixed position", "Moving"]}, {"desc": "From which angle did you shoot the video?", "name": "Shoot Angle", "type": "dropdown", "values": ["", "Frontal recording", "Tight angle: 10-40 degree", "Wide angle: 40-70 degree"]}, {"desc": "From which distance did you shoot the video?", "name": "Distance", "type": "dropdown", "values": ["", "Near/Selfie", "Mid (3-6 ft)", "Far (>6 ft)"]}, {"desc": "What is the video lighting direction?", "name": "Lighting Direction", "type": "dropdown", "values": ["", "Front lit", "Side lit", "Back lit"]}, {"desc": "What is the video background?", "name": "Background", "type": "dropdown", "values": ["", "Outdoors", "In office", "At home", "Plain background"]}, {"desc": "What is the topic in your speech?", "name": "Topic", "type": "dropdown", "values": ["", "Arts and Media", "Business", "Education", "Entertainment", "Food/Eating", "Nutrition", "Healthcare ", "High School Life", "Mental Health", "News", "Technology", "Morals and Ethics", "Phones and Apps", "Sports", "Science"]}]

我的任务是:“JSON 中的每个值、名称、描述都需要作为一行存储在表中”。

示例: id: 1, desc: "视频中有多少人？" id: 2, desc: "相机位置是多少？" 等等

我使用查询:

SELECT c.*, d.desc, d.name, d.values FROM source.table AS c, c.inputs AS d; 

出现错误:不允许在“输入”列上导航，因为它不是 super 类型

并查询:

从 source.table AS c、JSON_PARSE(c.inputs) AS d 中选择 c.*、d.desc、d.name、d.values；

给了我另一个错误:“FROM 中的函数表达式可能不会引用相同查询级别的其他关系”

但是当我将测试 JSON 创建为:

CREATE TABLE test_parse_json_super
(
  id smallint,
  details super
);
 
INSERT INTO test_parse_json_super VALUES(1, JSON_PARSE('[{"desc": "How many people does the video contain?", "name": "Number of People", "type": "dropdown", "values": ["", "Only 1", "2-3", "3+"]}, {"desc": "What is the camera position?", "name": "Movement", "type": "dropdown", "values": ["", "Fixed position", "Moving"]}, {"desc": "From which angle did you shoot the video?", "name": "Shoot Angle", "type": "dropdown", "values": ["", "Frontal recording", "Tight angle: 10-40 degree", "Wide angle: 40-70 degree"]}, {"desc": "From which distance did you shoot the video?", "name": "Distance", "type": "dropdown", "values": ["", "Near/Selfie", "Mid (3-6 ft)", "Far (>6 ft)"]}, {"desc": "What is the video lighting direction?", "name": "Lighting Direction", "type": "dropdown", "values": ["", "Front lit", "Side lit", "Back lit"]}, {"desc": "What is the video background?", "name": "Background", "type": "dropdown", "values": ["", "Outdoors", "In office", "At home", "Plain background"]}, {"desc": "What is the topic in your speech?", "name": "Topic", "type": "dropdown", "values": ["", "Arts and Media", "Business", "Education", "Entertainment", "Food/Eating", "Nutrition", "Healthcare ", "High School Life", "Mental Health", "News", "Technology", "Morals and Ethics", "Phones and Apps", "Sports", "Science"]}]'));
                                               

并使用官方 RedShift 文档中的查询“SELECT c.*, d.desc, d.name, d.values FROM test_parse_json_super AS c, c.details AS d;” - 工作正常来自 JSON 的所有数据都解析到每一行，并且 JSON 是正确的。

如何修复查询以使用我的真实数据？

谢谢。

Answer 1

我遇到了类似的问题。 json必须在创建的表中解析后才能使用，并且不能通过CTE或子查询引用然后使用。因此我认为答案是:

CREATE TABLE my_table_with_super 
AS 
(
  SELECT c.*, 
         JSON_PARSE(c.inputs) AS inputs_json_super 
  FROM source.table c
);

SELECT c.*, 
  json_row.desc, 
  json_row.name, 
  json_row.values
FROM my_table_with_super as c,
     c.inputs_json_super as json_row;