使用 clickhouse 遇到的一个奇怪问题

[wangshouh]

我使用 Clickhouse 进行 JSON 数据清洗，代码如下:

SELECT *
FROM
(
WITH JSONExtract(
	field, 
	'Tuple(transactions Nested(hash String, blockNumber String, value String, logs Nested(address String, data String, topics Array(String))))'
) AS parsed_json
SELECT 
	untuple(arrayJoin(tupleElement(parsed_json, 'transactions'))) as tx
FROM
	jsonTemp jt
LIMIT 5
)
LEFT ARRAY JOIN `tx.4`;

查询结果如下:

我使用以下代码创建了表:

CREATE TABLE logsTemp
(
	txHash String,
	txblockNumber String,
	value String,
	txlogs Tuple
	(
		address String,
		txlogsData String,
		topics Array(String)
	)
)
ENGINE = MergeTree
ORDER BY txblockNumber

使用以下代码执行插入操作:

INSERT INTO logsTemp 
SELECT * 
FROM 
(
  SELECT *
  FROM
  (
    WITH JSONExtract(
      field, 
      'Tuple(transactions Nested(hash String, blockNumber String, value String, logs Nested(address String, data String, topics Array(String))))'
    ) AS parsed_json
    SELECT 
      untuple(arrayJoin(tupleElement(parsed_json, 'transactions'))) as tx
    FROM
      jsonTemp jt
  )
  LEFT ARRAY JOIN `tx.4`
)

结果发现插入后 txlogsData 缺失，如下:

此处使用 Clickhouse 处于单机部署状态，版本为 22.13.1.1942

[wangshouh]

想办法自己解决了，怀疑是 `tuple` 的问题，所以在插入时进行了 `untuple` 操作，修正后的代码如下:

```sql
INSERT
INTO
logsTemp
SELECT
`tx.1`,
`tx.2`,
`tx.3`,
untuple(`tx.4`)
FROM
(
SELECT
*
FROM
(
WITH JSONExtract(
field,
'Tuple(transactions Nested(hash String, blockNumber String, value String, logs Nested(address String, data String, topics Array(String))))'
) AS parsed_json
SELECT
untuple(arrayJoin(tupleElement(parsed_json,
'transactions'))) as tx
FROM
jsonTemp jt
)
LEFT ARRAY
JOIN `tx.4`
)
```
但仍不明白为什么 tuple 会导致数据列丢失