I’m facing the error unexpected Parse response 'C' and searching on the internet I found out this error happens when rows are not closed after the previous query.
But in my case I’m only using QueryRow which return a *sql.Row where Close isn’t implemented.

type Queryable interface {
    QueryRow(query string, args ...interface{}) *sql.Row
}

func GetOrCreateArticle(q Queryable, article *entity.Article) (id int64, err error) {
    const selectQuery string = "SELECT id FROM articles WHERE link = $1"
    const insertQuery string = "INSERT INTO articles (link, title) VALUES ($1, $2) RETURNING id"

    err = q.QueryRow(selectQuery, article.Link).Scan(&id)
    fmt.Println("Error :", err, article.Link)

    if err == sql.ErrNoRows {
        return id, q.QueryRow(insertQuery, article.Link, article.Title).Scan(&id)
    }

    return id, err
}

Queryable is an interface to represent either a *sql.DB or *sql.Tx, here the function is always call with a Transaction.

In the same transaction I’m querying / inserting multiple Articles, the first call to this function always ends with the expeted result while the second always throw the error : pq : unexpected Parse response 'C'.