What experience do you have with the ClickHouse database?

ClickHouse is a columnar analytical database management system designed for high-speed processing of large volumes of data. In my experience working with ClickHouse, I used it for storing and analyzing logs and metrics in real-time. The main tasks included configuring tables with appropriate engines (such as MergeTree), optimizing queries for aggregations, and managing TTL for automatic deletion of old data.

In Go, I interacted with ClickHouse through drivers like github.com/ClickHouse/clickhouse-go, which allowed me to efficiently execute queries and process results. Here's an example of a simple insert and select query:

import (
    "database/sql"
    _ "github.com/ClickHouse/clickhouse-go"
    "log"
)

func example() {
    conn, err := sql.Open("clickhouse", "tcp://127.0.0.1:9000?debug=true")
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()

    // Insert data
    _, err = conn.Exec(`INSERT INTO visits (user_id, visit_date) VALUES (?, ?)`, 123, "2024-06-01")
    if err != nil {
        log.Fatal(err)
    }

    // Query data
    rows, err := conn.Query(`SELECT user_id, visit_date FROM visits WHERE user_id = ?`, 123)
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    for rows.Next() {
        var userID int
        var visitDate string
        if err := rows.Scan(&userID, &visitDate); err != nil {
            log.Fatal(err)
        }
        log.Printf("User %d visited on %s", userID, visitDate)
    }
}

It is also important to consider the features of ClickHouse, such as the lack of support for traditional transactions and its optimization for analytical queries, which influence application architecture.