postgresql – 如果不使用数据库挂起

我有一个我正在启动的Web应用程序.在启动时工作正常,但如果我离开它(比如说,一小时)并用另一个请求命中它,查询就会挂起.我想在每次查询之后关闭它然后打开一个新的连接,但是文档明确地说“关闭数据库是很少见的,因为数据库句柄意味着很长时间并且在许多goroutine之间共享.”我究竟做错了什么？

package main

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

var Db *sql.DB

func main() {
  var err error
  Db,err = sql.Open("postgres","user=me password=openupitsme host=my.host.not.yours dbname=mydb sslmode=require")
  if err != nil {
    log.Fatal("Cannot connect to db: ",err)
  }
  http.HandleFunc("/page",myHandler)
  http.ListenAndServe(":8080",nil)
}

func myHandler(w http.ResponseWriter,r *http.Request) {
  log.Println("Handling Request....",r)
  query := `SELECT pk FROM mytable LIMIT 1`
  rows,err := Db.Query(query)
  if err != nil {
    log.Println(err)
  }
  defer rows.Close()
  for rows.Next() {
    var pk int64
    if err := rows.Scan(&pk); err != nil {
      log.Println(err)
    }
    log.Println(pk)
  }
  log.Println("Request Served...")
}

编辑#1：
我的postgres日志显示：

2015-07-08 18:10:01 EDT [7710-1] user@here LOG:  could not receive data from client: Connection reset by peer
2015-07-08 18:20:01 EDT [7756-1] user@here LOG:  could not receive data from client: Connection reset by peer