Impala分析函數在where子句中

Question

所以問題的基本前提是我在hadoop中有一些巨大的表格，我需要從每個月獲取一些樣本。我嘲笑了下方顯示排序後，我的事情，但顯然它不是真實的數據...

--Create the table 
CREATE TABLE exp_dqss_team.testranking (
    Name STRING, 
    Age INT, 
    Favourite_Cheese STRING 
) STORED AS PARQUET; 

--Put some data in 
INSERT INTO TABLE exp_dqss_team.testranking 
VALUES (
    ('Tim', 33, 'Cheddar'), 
    ('Martin', 49, 'Gorgonzola'), 
    ('Will', 39, 'Brie'), 
    ('Bob', 63, 'Cheddar'), 
    ('Bill', 35, 'Brie'), 
    ('Ben', 42, 'Gorgonzola'), 
    ('Duncan', 55, 'Brie'), 
    ('Dudley', 28, 'Cheddar'), 
    ('Edmund', 27, 'Brie'), 
    ('Baldrick', 29, 'Gorgonzola')); 

我想要得到的是像最年輕的2人在每個類別的奶酪。下面讓我對每個類別的奶酪歲的排名，但不會將其限制前兩名：

SELECT RANK() OVER(PARTITION BY favourite_cheese ORDER BY age asc) AS rank_my_cheese, favourite_cheese, name, age 
FROM exp_dqss_team.testranking; 

如果我添加一個WHERE條款它給了我下面的錯誤：

WHERE clause must not contain analytic expressions

SELECT RANK() OVER(PARTITION BY favourite_cheese ORDER BY age asc) AS rank_my_cheese, favourite_cheese, name, age 
FROM exp_dqss_team.testranking 
WHERE RANK() OVER(PARTITION BY favourite_cheese ORDER BY age asc) <3; 

有沒有更好的方法來做到這一點比創建一個所有排名表，然後從排名WHERE條款選擇？

Answer 1

你可以試試嗎？

select * from (
SELECT RANK() OVER(PARTITION BY favourite_cheese ORDER BY age asc) AS rank_my_cheese, favourite_cheese, name, age 
FROM exp_dqss_team.testranking 
) as temp 
where rank_my_cheese <= 2;