从网上找到资料,原来对于大数据量的分页,都不用skip+limit的,是通过改变查询规则来起到分页的效果。由于不用略过,所以无聊数据量有多大,时间复杂度的波动不大。
这个是根据,实现原理是通过数据库主键ID来进行查询分页
    //操作数据库帮助类
        protected MongoDBConnector_Local_NoAuth conn = new MongoDBConnector_Local_NoAuth();
   //存放分页连对应主键ID,然后通过ID进行查询
        protected Dictionary<int, int> docId = new Dictionary<int, int>();
        /// <summary>
        /// 获取数据并进行分页计算
        /// </summary>
        /// <param name="t">这个用户查询</param>
        /// <param name="PageSize">分页大小</param>
        /// <param name="CurrentPageIndex">当前页数</param>
        /// <param name="PageLink">分页的页面:比如Default.aspx</param>
        /// <param name="homepage">这个是输出参数,输出分页连</param>
        /// <returns>查询到数据</returns>
    public IList<Answer> GetList(string t, int PageSize, int CurrentPageIndex, string PageLink, out string homepage)
        {
            //获取数据库
            MongoDatabase database = conn.DataBase_Select_ReturnDB("Ask");
            //获取数据
            MongoCollection<Answer> mcollection = database.GetCollection<Answer>("Answer");
            QueryConditionList query = null;//定义查询条件
            int id = 0;
            object obj = HttpContext.Current.Session["ids"];//读取缓存数据
        //缓存为空,重新开始查询
            if (object.Equals(obj, null))
            {
                query = Query.GT("ID", 0);
            }//分页连处理
            else if (CurrentPageIndex ==1) 
            {
                query = Query.GT("ID", 0);
            }
            else
            {//读取条件生成查询
                Dictionary<int, int> docKey = obj as Dictionary<int, int>;
                id = docKey[CurrentPageIndex];
                query = Query.GT("ID", id);
            }
            int recordCount = Convert.ToInt32(mcollection.Count());
            int mpage = recordCount / PageSize + (recordCount % PageSize > 0 ? 1 : 0);
            int PageNo = Math.Min(Convert.ToInt32(start) / PageSize + 1, mpage);
            homepage = PageLink_aspx(PageLink, t, CurrentPageIndex, recordCount, mpage);
            MongoCursor<Answer> mcursor = mcollection.Find(query).SetLimit(20).SetSortOrder(SortBy.Ascending("ID"));
            //判断1到6页 不变
            if (CurrentPageIndex - 6 <= 0)
            {
                query = Query.GT("ID", 1);
                IList<Answer> alist = mcollection.Find(query).SetLimit(220).SetSortOrder(SortBy.Ascending("ID")).ToList<Answer>();
                int cnt = alist.Count();
                int index = 0;
                int page = cnt / 20;
                for (int i = 0; i < page; i++)
                {
                    index = i + 1;
                    docId.Add(index, alist[i * 20].ID);
                }
                int ys = cnt % 20;
                if (ys != 0)
                    docId.Add(index + 1, alist[cnt - ys].ID);
                HttpContext.Current.Session["ids"] = docId;
            }
            else
            {
                //处理左边数据
                docId.Clear();
                query = Query.LTE("ID", id);
                IList<Answer> alist_left = mcollection.Find(query).SetLimit(120).SetSortOrder(SortBy.Descending("ID")).ToList<Answer>();
                int start_left = CurrentPageIndex - 6;
                int cnt_left = alist_left.Count;
                int page_left = cnt_left / 20;
                for (int i = page_left-1; i>=0; i--)
                {
                    start_left = start_left + 1;
                    docId.Add(start_left, alist_left[i * 20].ID);
                }
                int ys_left = cnt_left % 20;
                if (ys_left != 0)
                    docId.Add(start_left + 1, alist_left[cnt_left - ys_left].ID);
                //获取分页连右边数据
                query = Query.GT("ID", id);
                IList<Answer> alist_right = mcollection.Find(query).SetLimit(120).SetSortOrder(SortBy.Ascending("ID")).ToList<Answer>();
                int start_right = start_left;
                int cnt_right = alist_right.Count;
                int page_right = cnt_right / 20;
                for (int i = 0; i < page_right; i++)
                {
                    if (i == 0)
                        continue;
                    start_right = start_right + 1;
                    docId.Add(start_right, alist_right[i * 20].ID);
                }
                int ys_right = cnt_left % 20;
                if (ys_left != 0)
                    docId.Add(start_right + 1, alist_right[cnt_right - ys_right].ID);
                HttpContext.Current.Session["ids"] = docId;
            }
            return mcursor.ToList<Answer>();
        }
        /// <summary>
        /// 动态分页链接
        /// </summary>
        /// <param name="HomePageStr">分页页面名称</param>
        /// <param name="t">查询条件做URL地址进行传参</param>
        /// <param name="PageNo">当前页数</param>
        /// <param name="totalCnt">总记录数</param>
        /// <param name="mpage">总页数</param>
        /// <returns></returns>
        public string PageLink_aspx(string HomePageStr, string t, int PageNo, int totalCnt, int mpage)
        {
            int i, j, k;
            string homelink;
            string homepage;
            homepage = "";
            homelink = HomePageStr
;
            homepage = homepage + "第 " + (PageNo).ToString() + " / " + mpage.ToString() + " 页  共" + totalCnt + "条 ";
            if (PageNo > 1)
            {
                homepage += " <a href=\"" + homelink + "?start=1" + t + "\">首页</a> ";
                homepage = homepage + " <a href=\"" + homelink + "?start=" + Convert.ToString((PageNo - 1)) + t + "\">上一页 </a> ";
            }
            else { homepage = homepage + " <font color=\"#999999\" >上一页 </font> "; }
            if (PageNo <= 5)
            {
                i = 1;
            }
            else
            {
                i = PageNo - 5;
            }
            k = i + 10;
            if (k > mpage) { k = mpage; }
            for (j = i; j <= k; j++)
            {
                if (j == PageNo) { homepage = homepage + "<b><font color=\"#ff0000\" >" + Convert.ToString(j) + "</font></b> "; }
                else if (j == 1) { homepage = homepage + "<a href=\"" + homelink + "?start=1" + t + "\" >[" + Convert.ToString(j) + "]</a> "; }
                else { homepage = homepage + "<a href=\"" + HomePageStr + "?start=" + j + t + "\">[" + Convert.ToString(j) + "]</a> "; }
            }
            if (PageNo < mpage)
            {
                homepage = homepage + " <a href=\"" + HomePageStr + "?start=" + Convert.ToString((PageNo + 1)) + t + "\">下一页</a> ";
                homepage += " <a href=\"" + HomePageStr + "?start=" + mpage + t + "\">最后一页</a> ";
            }
            else { homepage = homepage + " <font color=\"#999999\" >下一页</font> "; }
            return homepage;
        }

  

由于作者没有实现最后一页的功能,不过代码看到这也有了一定的理解,所以要靠自己动手啦
posted on 2012-09-20 16:13  杨斐_Feil  阅读(2232)  评论(1编辑  收藏  举报