ClickHouse / ClickHouse/clickhouse-java
Regression on format JSONEachRow with JDBC v2
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Descripción
## 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)
Guía de contribución
Línea de trabajo
Reproduce the failure with the JDBC v2 driver using `SELECT * FROM table FORMAT JSONEachRow;`, then compare its handling with JDBC v1 and the `formatRowNoNewline` workaround. Trace the JDBC v2 output-format handling from `ClickHouseDataSource` and the query execution path; done means streamed JSONEachRow results work without the exception, or the supported formats and workaround are documented.
Escrito por el modelo de indexación a partir del texto del issue.
Evaluación
- Stack tecnológico
- java, sql
- Área
- database
- Tipo de issue
- Error
- Dificultad
- 4/5
- Tiempo estimado
- 3-5 días
- Estado de actividad
- Tranquilo
- Claridad
- Bastante claro
- Aptitud para principiantes
- 52/100