Incorrect parsing of complex types (Arrays and Tuples)

Here are some cases that I’ve found (rs is a ResultSet instance):

1. Tuple:

   select ('1', 2) as a;
   

   can only be extracted as String:

   rs.getMetaData.getColumnTypeName(1) = "Tuple(String, UInt8)"
   rs.getObject(1) = "('1',2)"
   

2. Nested arrays:

   select [[1,2], [3,4]] as a;
   

   cannot be extracted as Array:

   rs.getMetaData.getColumnTypeName(1) = "Array(Array(UInt8))"
   rs.getObject(1) // Method threw 'java.lang.RuntimeException' exception.
                              // Parse exception: ByteFragment{[[[1,2],[3,4]]], start=0, len=13}
   rs.getArray(1) // Method threw 'java.lang.IllegalStateException' exception.
   

3. Tuples nested in Array:

   select [('a',1), ('b', 2)] as a;
   

   strange parsing behavior when parsed as Array:

   rs.getMetaData.getColumnTypeName(1) = Array(Tuple(String, UInt8))
   rs.getArray(1)={ru.yandex.clickhouse.ClickHouseArray}:
          array = {java.lang.String[4]@3644} 
          0 = "('a'"
          1 = "1)"
          2 = "('b'"
          3 = "2)"
   

[serebrserg]

Thanks. Currently the driver has just a basic arrays support. All of cases you listed are expected. I’ll check what can be done on that.

[zhicwu]

I cannot find ClickhouseTuple implementation in ClickHouse JDBC as of version 0.3.1-patch, the tuple may a suitable type for compound type.

Most data types including Tuple and mixed use of Array, Map and Tuple etc. are supported on develop branch. But it’s still experimental and only works with gRPC and RowBinary format at the moment, for example:

// create table test_table(
//   array_column Array(Tuple(UInt8, LowCardinality(String))),
//   array_tuple Tuple(Map(String, String), String)
// )engine=Memory

// insert into test_table values([(1,'a'), (2,'b')], ({'a':'1','b':'2'},'c'))

ClickHouseNode server = ClickHouseNode.of("localhost", ClickHouseProtocol.GRPC, 9100, "default");
try (ClickHouseClient client = ClickHouseClient.newInstance(server.getProtocol());
    ClickHouseResponse resp = client.connect(server).format(ClickHouseFormat.RowBinaryWithNamesAndTypes)
      .query("select * from test_table").execute().get()) {
    for (ClickHouseRecord r : resp.records()) {
      List<?>[] array = (List<?>[]) r.getValue(0).asObject();
      List<?> tuple = r.getValue(1).asObject(List.class);

      Map<String, String> map = (Map<String, String>) tuple.get(0);
      ...
    }
}

JDBC driver will be enhanced accordingly.