Db Connection Not Closed (ARCH5084)

Key go.performance.db-connection-not-closed · Severity error · Category performance

If the *sql.Rows returned by a query is never closed, the underlying connection is not returned to the pool and the pool drains. Close it with defer rows.Close().

Incorrect

func ids(db *sql.DB) ([]int, error) {
  rows, err := db.Query("SELECT id FROM users")
  if err != nil {
    return nil, err
  }
  var out []int
  for rows.Next() {
    var id int
    rows.Scan(&id)
    out = append(out, id)
  }
  return out, nil
}

Correct

func ids(db *sql.DB) ([]int, error) {
  rows, err := db.Query("SELECT id FROM users")
  if err != nil {
    return nil, err
  }
  defer rows.Close()
  var out []int
  for rows.Next() {
    var id int
    rows.Scan(&id)
    out = append(out, id)
  }
  return out, nil
}

Fix

Add defer rows.Close() after opening the *sql.Rows or connection.