[BUG] - JDBC driver loses data when JSONEachRow is used

[jonathanyuechun]

Hi,

It seems that a fix was proposed for this issue:

#475

but didnt had the chance to get merged.

This issue still exists in: https://github.com/ClickHouse/clickhouse-jdbc/tree/v0.3.1

Below a snippet:

  public static void main(String... args) throws SQLException {
    String url = "jdbc:clickhouse://localhost:8123/tutorial";
    ClickHouseProperties properties = new ClickHouseProperties();
    // set connection options - see more defined in ClickHouseConnectionSettings
    properties.setClientName("Agent #1");
    // set default request options - more in ClickHouseQueryParam
    properties.setSessionId("default-session-id");
    ClickHouseDataSource dataSource = new ClickHouseDataSource(url, properties);

    String sql = "select * from visits_v1 LIMIT 10 format JSONEachRow";
    Map<ClickHouseQueryParam, String> additionalDBParams = new HashMap<>();
    // set request options, which will override the default ones in ClickHouseProperties
    additionalDBParams.put(ClickHouseQueryParam.SESSION_ID, "new-session-id");
    List<String> datas = new ArrayList<>();
    try (ClickHouseConnection conn = dataSource.getConnection();
        ClickHouseStatement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql, additionalDBParams)) {
      while (rs.next()) {
        datas.add(rs.getString(1));
      }
    }
    // expected 10 but returned 8
    System.out.println(datas.size());
  }

[zhicwu]

Thanks for reporting. Currently the driver relies on TabSeparatedWithNamesAndTypes format and it does not support other formats well(especially those without headers). This will be fixed in next release.

[zhicwu]

select * from numbers(11) LIMIT 10 format JSONEachRow works for me, but this function is currently limited to http protocol - grpc does not support query with custom format.