ClickHouse / ClickHouse/clickhouse-java

Regression on format JSONEachRow with JDBC v2

未关闭
#2,799 4 条评论 0 个 reaction 已指派 0 人 在 GitHub 查看
bug jdbc-v2
主要语言
Java
星标
1.6k
派生
636
平均合并
2 天 23 小时
30 天内合并 PR
29

描述

## Description

(1) `SELECT * FROM table FORMAT JSONEachRow;`

gives

`SQL-Exception [HY000]: Only RowBinaryWithNameAndTypes is supported for output format. Please check your query.`

after Transition to JDBC driver v2 (tested with driver version 0.9.7).

### Moreover

When returning to v1 using driver Property` clickhouse.jdbc.v1=true` the select works as expected.
Also, the desired behaviour is produced (under v2) by the alternative select

(2) `SELECT formatRowNoNewline( 'JSONEachRow', * ) AS result FROM table;`

but none if these is documented in either [(https://clickhouse.com/docs/integrations/language-clients/java/jdbc#migration-guide](https://clickhouse.com/docs/integrations/language-clients/java/jdbc#migration-guide) or, more generally, here [https://clickhouse.com/docs/integrations/language-clients/java/jdbc](https://clickhouse.com/docs/integrations/language-clients/java/jdbc)

(Thus, as a - potentially cheap - alternative to fixing this regression, please document supported FORMAT specifiers and supported variations/workarounds)

See Expected Behaviour section below for an argument, why (2) cannot currently serve as a replacement for (1) on large tables.

### Steps to reproduce

Call
`SELECT * FROM table FORMAT JSONEachRow;`
on any (non empty) table.

### Error Log or Exception StackTrace

```
SQL-Exception [HY000]: Only RowBinaryWithNameAndTypes is supported for output format. Please check your query.
```

### Expected Behaviour

Return the row as Json Object: '{"' colname1 '"="' colvalue1 '", ' ....

Also

`SELECT formatRowNoNewline( 'JSONEachRow', * ) AS result FROM table;`

returns the desired result BUT processes each row to JSON _first_ and is thus not streaming compatible, whereas

`SELECT * FROM table FORMAT JSONEachRow;`

applies JSON formating _on the fly_, while returning results. Big difference on big tables.

### Code Example

```java
public static void main(String[] args) {

try(Connection conn = new ClickHouseDataSource(dburl, props).getConnection(user, pass)) {

Statement statement = conn.createStatement();

final String selectStatement = "SELECT * FROM test_table FORMAT JSONEachRow;";

ResultSet resultSet = statement.executeQuery(selectStatement);
while (resultSet.next()) {
System.out.println(resultSet.getString(1));
}

} catch (Exception x) {
x.printStackTrace();
}
}
```

### Configuration

#### Environment
* Client version: clickhouse-jdbc-0.9.7-all.jar
* Language version: Java 17
* OS: tried on Windows and Linux

#### ClickHouse Server
* ClickHouse Server version: 25.6.4.12
* ClickHouse Server non-default settings, if any: %
* `CREATE TABLE` statements for tables involved: Use any.
* Sample data for all these tables, use [clickhouse-obfuscator](https://github.com/ClickHouse/ClickHouse/blob/master/programs/obfuscator/Obfuscator.cpp#L42-L80) if necessary

P.S.: This was first reported in the ClickHouse Server tracker as [99852](https://github.com/ClickHouse/ClickHouse/issues/99852)

贡献指南

打开贡献指南

调研方向

使用 JDBC v2 驱动程序和 `SELECT * FROM table FORMAT JSONEachRow;` 重现该故障,然后将其处理方式与 JDBC v1 以及 `formatRowNoNewline` 这一变通方案进行比较。从 `ClickHouseDataSource` 和查询执行路径开始跟踪 JDBC v2 的输出格式处理;当流式 JSONEachRow 结果能够在不抛出异常的情况下正常工作,或已记录受支持的格式和变通方案时,即视为完成。

由索引模型根据 Issue 内容生成。

评估

技术栈
java, sql
领域
database
Issue 类型
缺陷
难度
4/5
预计耗时
3-5 天
活跃度
冷清
描述清晰度
基本清楚
新手友好度
52/100

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。