如何通过将部分行变为列来在 Clickhouse 中制作 pivot_wider (r) / pivot (pandas)？

Question

我有一个table喜欢：

event_id	date	event_name	key	value
1	'2021-01-01'	'session_start'	'session_id'	'12345'
1	'2021-01-01'	'session_start'	'network'	'organic'
1	'2021-01-01'	'session_start'	'screen_id'	'22'
1	'2021-01-01'	'session_start'	'any_var'	'True'
2	'2021-01-02'	'app_deleted'	'session_id'	'23456'
2	'2021-01-02'	'app_deleted'	'network'	'organic'
2	'2021-01-02'	'app_deleted'	'screen_id'	'33'

我想将它变成具有更多列的 table 并减少行数，以便 'key' 值成为列，而 'value' - 的值这些列，设置 NULL，其中值将为空。总共会有 ~ 100 列。

event_id	date	event_name	session_id	network	screen_id	any_var
1	'2021-01-01'	'session_start'	'12345'	'organic'	'22'	'True'
1	'2021-01-02'	'app_deleted'	'23456'	'organic'	'33'	NULL

谢谢！

P.S。我自己想不出数组的解决方案

P.P.S 不幸的是，密钥可能不同，而且每个月都不同

Answer 1

SELECT
    event_id,
    date,
    event_name,
    anyIf(toNullable(value), key = 'session_id') AS session_id,
    anyIf(toNullable(value), key = 'network') AS network,
    anyIf(toNullable(value), key = 'screen_id') AS screen_id,
    anyIf(toNullable(value), key = 'any_var') AS any_var
FROM b
GROUP BY
    event_id,
    date,
    event_name;

┌─event_id─┬───────date─┬─event_name────┬─session_id─┬─network─┬─screen_id─┬─any_var─┐
│        1 │ 2021-01-01 │ session_start │ 12345      │ organic │ 22        │ True    │
│        2 │ 2021-01-02 │ app_deleted   │ 23456      │ organic │ 33        │ ᴺᵁᴸᴸ    │
└──────────┴────────────┴───────────────┴────────────┴─────────┴───────────┴─────────┘


create table b (event_id int, date date, event_name String, key String, value String) Engine=Memory;

insert into b values
(1 ,'2021-01-01','session_start','session_id','12345')
(1,'2021-01-01','session_start','network','organic')
(1,'2021-01-01','session_start','screen_id','22')
(1,'2021-01-01','session_start','any_var','True')
(2,'2021-01-02','app_deleted','session_id','23456')
(2,'2021-01-02','app_deleted','network','organic')
(2,'2021-01-02','app_deleted','screen_id','33')

Answer 2

SQL 不允许列数可变。每行有相同数量的列。列数、它们的名称和类型在执行查询之前是已知的。

SELECT
    event_id,
    date,
    event_name,
    groupArray((key, value))
FROM b
GROUP BY
    event_id,
    date,
    event_name
┌─event_id─┬───────date─┬─event_name────┬─groupArray(tuple(key, value))────────────────────────────────────────────────────────┐
│        1 │ 2021-01-01 │ session_start │ [('session_id','12345'),('network','organic'),('screen_id','22'),('any_var','True')] │
│        2 │ 2021-01-02 │ app_deleted   │ [('session_id','23456'),('network','organic'),('screen_id','33')]                    │
└──────────┴────────────┴───────────────┴──────────────────────────────────────────────────────────────────────────────────────┘

如何通过将部分行变为列来在 Clickhouse 中制作 pivot_wider (r) / pivot (pandas)？

How to make pivot_wider (r) / pivot (pandas) in clickhouse by mutating part of the rows into columns?

sql

clickhouse