How can I specify NULL for a nullable column in columnar insert?

[roengram]

Hi, I'm trying to insert data to ClickHouse using columnar insert, referencing: https://github.com/ClickHouse/clickhouse-go/blob/main/examples/clickhouse_api/columnar_insert.go

The example works but I'd like to specify NULL so that the default value will be used.
I tried inserting a nil for NULL, but the insert results is not the default value but empty string.
Can anybody tell me how I specify NULL?

package main

import (
	"context"
	"fmt"
	"os"

	"github.com/ClickHouse/clickhouse-go/v2"
)

func main() {
	conn, err := clickhouse.Open(&clickhouse.Options{
		Addr: []string{fmt.Sprintf("172.27.0.3:9000")},
		Auth: clickhouse.Auth{
			Database: "default",
		},
	})
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	ctx := context.Background()

	batch, err := conn.PrepareBatch(ctx, "INSERT INTO test")
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	var (
		col []*string
	)
	for i := 0; i < 5; i++ {
		str := fmt.Sprintf("I am %d", i)
		if i == 2 {
			col = append(col, nil)  // append nil for NULL
			continue
		}
		col = append(col, &str)
	}
	if err := batch.Column(0).Append(col); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	if err := batch.Send(); err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
}

Insert retuls

{                                                                                                                                                                                                            
        "meta":                                                                                                                                                                                              
        [                                                                                                                                                                                                    
                {                                                                                                                                                                                            
                        "name": "type",                                                                                                                                                                      
                        "type": "String"                                                                                                                                                                     
                }
        ],

        "data":
        [
                {
                        "type": ""
                },
                {
                        "type": "I am 0"
                },
                {
                        "type": "I am 1"
                },
                {
                        "type": "I am 3"
                },
                {
                        "type": "I am 4"
                }
        ],

        "rows": 5,

        "statistics":
        {
                "elapsed": 0.001170489,
                "rows_read": 12,
                "bytes_read": 76
        }
}

Table schema

DESCRIBE TABLE test
FORMAT tabseparated

Query id: 11206e7f-5873-4e86-8a8a-4e77813646a5

type    String  DEFAULT \'real\'                ZSTD(1)

1 row in set. Elapsed: 0.000 sec. 

[jkaflik]

Hi @roengram

Unfortunately this is a limitation of ClickHouse Native format: ClickHouse/ClickHouse#58662
There is no work around for this.