在PostreSQL中汇总hstore列 [英] Aggregate hstore column in PostreSQL

问题描述

我有一个这样的表：

                         Table "public.statistics"

id         | integer                | not null default nextval('statistics_id_seq'::regclass)
goals      | hstore                 | 

项目：

|id    |goals                  |
|30059 |"3"=>"123"             |
|27333 |"3"=>"200", "5"=>"10"  |

我需要做的是通过键入哈希值来汇总所有值吗？

What I need to do for aggregate all values by key in hash?

我想得到这样的结果：

select sum(goals) from statistics

返回

|goals                 |
|"3"=>"323", "5"=>"10" |

推荐答案

基于Laurence的答案，这是一种纯SQL方法使用 array_agg 和 hstore将总的键/值对汇总为新的 hstore []，text []）构造函数。

Building on Laurence's answer, here's a pure SQL way to aggregate the summed key/value pairs into a new hstore using array_agg and the hstore(text[], text[]) constructor.

http://sqlfiddle.com/#!1/9f1fb/17

SELECT hstore(array_agg(hs_key), array_agg(hs_value::text))
FROM (
  SELECT
    s.hs_key, sum(s.hs_value::integer)
  FROM (
    SELECT (each(goals)).* FROM statistics
  ) as s(hs_key, hs_value)
  GROUP BY hs_key
) x(hs_key,hs_value)

我还用简单的强制转换为整数替换了 to_number 并简化了键/值迭代。

I've also replaced to_number with a simple cast to integer and simplified the key/value iteration.

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