Reproducing ClickHouse Client CLI query result format using Golang ClickHouse library

Question

Clickhouse CLI result

When performing a query using the clickhouse-client command line interface and setting the format as JSON, we not only obtain the result but also statistics.

Command

clickhouse-client --password=test --user=default --format=JSON --query="select 1 + 1"

Result

{
    "meta":
    [
        {
            "name": "plus(1, 1)",
            "type": "UInt16"
        }
    ],

    "data":
    [
        {
            "plus(1, 1)": 2
        }
    ],

    "rows": 1,

    "statistics":
    {
        "elapsed": 0.001043427,
        "rows_read": 1,
        "bytes_read": 1
    }
}

I tried using the official ClickHouse library in Golang (github.com/ClickHouse/clickhouse-go/v2) but was unsuccessful in achieving the desired result.

If anyone has successfully obtained a JSON response using the Golang library, I would appreciate any insights or solutions shared.

Difficult to help without seeing a sample of your code

Rich Raposa
– Rich Raposa

2023-08-22 15:22:02 +00:00
Commented Aug 22, 2023 at 15:22 — Rich Raposa
– Rich Raposa, Commented Aug 22, 2023 at 15:22

Rich Raposa · Accepted Answer · 2023-08-23 14:15:38Z

0

When you a run a query using the Go client, specifying a format like JSON probably isn't going to work like you would expect. If you want to output the result in JSON, then you need to process each row and convert it to JSON.

It's actually not too difficult if you use the encoding/json library. Put the results in a Struct and use the json.MarshalIndent function:

    var r struct {
         Name string `ch:"Name"`
         Uuid_str string `ch:"Uuid_str"`
    }
    ctx := context.Background()
    err = conn.QueryRow(ctx, "SELECT name as Name,toString(uuid) as Uuid_str FROM system.tables LIMIT 1").ScanStruct(&r)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(r)
    file, _ := json.MarshalIndent(r, "", " ")
    _ = ioutil.WriteFile("test.json", file, 0644)

The result in test.json was:

{
 "Name": "COLUMNS",
 "Uuid_str": "00000000-0000-0000-0000-000000000000"
}

answered Aug 23, 2023 at 14:15

Rich Raposa

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1 Comment

calebeaires Over a year ago

The goal is not to specifically obtain the result in JSON format. Instead, the objective is to retrieve the identical outcome that is obtained when using the --format=JSON option in clickhouse-client or the ClickHouse HTTP interface. This outcome comprises the following components mentioned in the question: meta, data, rows, and statistics.

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