Have you worked with PostgreSQL, MongoDB, ClickHouse, and other databases?

Yes, I have worked with PostgreSQL, MongoDB, and ClickHouse.

• PostgreSQL was used for relational data, complex queries with JOINs, transactions, and ensuring data integrity. I used ORM and native drivers in Go.
• MongoDB was used for storing documents with a dynamic schema, where the data structure often changes, as well as for rapid prototyping.
• ClickHouse was used for analytical tasks and processing large volumes of data with high read speed.

Example of connecting to PostgreSQL in Go using database/sql and the pq driver:

import (
    "database/sql"
    _ "github.com/lib/pq"
)

func connectPostgres() (*sql.DB, error) {
    connStr := "user=username dbname=mydb sslmode=disable"
    db, err := sql.Open("postgres", connStr)
    if err != nil {
        return nil, err
    }
    return db, nil
}