我在 ClickHouse 中有以下架构的数据:
CREATE TABLE table AS (
key String,
…
nested Nested (
key String,
value String
)
) …
一些示例数据:
key | … | nested |
----|---|-------------------------------|
k1 | | [{"key": "a", "value": "1"}] |
k1 | | [{"key": "a", "value": "2"}] |
k1 | | [{"key": "a", "value": "1"}, |
| | "key": "a", "value": "2"}] |
k1 | | [{"key": "b", "value": "3" |
我想按键分组并将所有不同的键值对收集到两个数组中:
key | nested.key | nested.value |
------|-----------------|------------------|
k1 | ["a", "a", "b"] | ["1", "2", "3"] |
在 ClickHouse 中执行此操作的最简单、最有效的方法是什么?
最佳答案
我会建议这个查询:
SELECT DISTINCT
key,
arrayDistinct(groupArray((nested.key, nested.value))) AS distinctNested,
arrayMap(x -> (x.1), distinctNested) AS `nested.keys`,
arrayMap(x -> (x.2), distinctNested) AS `nested.values`
FROM test.table_002
ARRAY JOIN nested
GROUP BY key
/* Result
┌─key─┬─distinctNested──────────────────┬─nested.keys───┬─nested.values─┐
│ k1 │ [('a','1'),('a','2'),('b','3')] │ ['a','a','b'] │ ['1','2','3'] │
└─────┴─────────────────────────────────┴───────────────┴───────────────┘
*/
/* Test data preparing */
CREATE TABLE test.table_002 (
key String,
nested Nested (key String, value String)
) ENGINE = Memory;
INSERT INTO test.table_002
FORMAT JSONEachRow
{"key": "k1", "nested.key":["a"], "nested.value": ["1"]}
{"key": "k1", "nested.key":["a"], "nested.value": ["2"]}
{"key": "k1", "nested.key":["a", "a"], "nested.value": ["1", "2"]}
{"key": "k1", "nested.key":["b"], "nested.value": ["3"]}
关于sql - 将 ClickHouse 中嵌套类型的不同键值对收集到数组中,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/57595840/