PostgreSQL处理jsonb中的arrays of array 类型

一、提出问题

在postgre数据库，遇到了数组内嵌套数组的jsonb存储格式，如下：

SELECT *
FROM public.keyword_trend

查询结果：
其中，history一栏[[“2014-05-11”,70],[“2014-05-18”,69]…]中，每个数组包含两项，分别为日期和得分，我们希望查询最近得分（2019年2，3，4月平均得分）环比增长大于100%的keyword。

二、解决方法

先上代码：

with t1 as ( 
    select keyword,to_date(h->>0,'YYYY MM DD') as day,(h->>1)::integer as num
    from keyword_trend as t, jsonb_array_elements(history) as h
), t2 as(
    select keyword,extract(year from day)::integer as year,
             extract(month from day)::integer as month,
             extract(day from day)::integer as day,num
    from t1
), t3 as (
    select keyword,year,avg(num)
    from t2
    where year in (2018,2019) and month in (2,3,4)
    group by keyword,year
),t4 as (
    select t31.keyword,t31.avg as avg_2019,t32.avg as avg_2018
    from t3 as t31 cross join t3 as t32
    where t31.keyword=t32.keyword and t31.year>t32.year
)
select * 
from t4
where avg_2019-2*avg_2018 >0

• t1：拆开history，使其竖向排列
• t2：对日期的处理，将年月日提取出来
• t3：筛选出计算环比需要用到的数据
• t4：自连接得到一个三列的表：keyword，avg_2019,avg_2018
• t5：选出环比增长大于100%的keyword

查询结果如下：