数据库设计 - “推送”模型或扇出字段 [英] Database Design - "Push" Model, or Fan-out-on-write
问题描述
背景信息：
我正在尝试检索我关注的人的图片，按照最新时间排序。这就像一个twitter新闻饲料，他们显示你的朋友最新的饲料。
I'm trying to retrieve images from people I follow, sort by latest time. It's like a twitter news feed where they show the latest feed by your friends.
计划：
目前我只需要保留一个项目考虑，这是图像。在未来，我打算分析用户的行为，并将他们可能喜欢的其他图片添加到他们的Feed等。
Currently there is only 1 item i need to keep in consideration, which is the images. In future i'm planning to analyse user's behavior and add in other images they might like into their feed, etc.
http://www.quora.com/What-are-best-practices-for-building-something-like-a-News-Feed
我个人觉得拉模型，或者说，风扇输出负载，其中我实时拉所有信息将是最糟糕的推模型。因为想象我有100个以下，我将不得不提取和排序的时间。 （让我知道如果我错了，例如，读是比写（推模型）100倍
I personally feel that "Pull" Model, or Fan-out-on-load where i pull all info at real time would be worst than the push model. Because imagine i have 100 following, i would have to fetch and sort by time. (Let me know if i'm wrong eg, Read is 100x better than Write(Push Model)
我推动的推模型的当前设计如下
The current design of the push model i have in mind is as follows
Table users_feed(ID, User_ID, Image_ID,datetime)
选项1：存储Image_ID列表
Option 1 : Store A list of Image_ID
存储一个图片ID和重复的行（更多具有相同User_ID但不同Image_ID的行）
Option 2 : Store one image ID and duplicate rows(More Rows of same User_ID but different Image_ID)
计划是限制用户在此Feed中可以拥有的每一行，这意味着，总是会有最多50张图片，如果他们想要更多的项目超过50图像在他们的新闻源。他们不能（我可能编码一个替代存储更多，以便将来可以查看更多）
The plan is to limit each Row a user can have in this feed , which means , there would always be a max of 50 images. If they want more items beyond the 50 images in their news feed. They cant(I might code a alternative to store more so they can view more in future)
问题1
由于当用户关注用户将一个项目添加到他们的
Since when user following users add a item into their "collection" i have to push it into each of their follower's feed. Wont there be a problem in Write? 200 followers = 200 writes?
问题2
哪种方法对我来说会更好，因为我只有一种类型的数据是图像。图片的Feed。
Which method would be better for me keeping in consideration that i only have one type of data which is images. Feeds of images.
问题3
如果我选择存储Feed提前（推方法）我怎么实际写它到我所有的朋友？
If i choose to store the feed in advance(push method) how do i actually write it into all my friends?
Insert xxx into feeds whereIn (array of FriendsID)?
任何形式的意见将非常感谢。提前感谢！
Any form of advice would be greatly appreciated. Thanks in advance!
推荐答案
我建议您按拉方法 ，原因如下：
I would recommend you to follow pull method over push method for the following reasons:
-
这将为未来的扩展提供更多自由。
It gives to more freedom for extencibility in the future.
减少写入次数（假设有10M个关注者，则必须有
，10M只写入1个帖子）。
Less number of writes ( imagine 10M followers then there has to be
10M writes for just 1 post).
您可以通过类似于以下查询获取用户的所有Feed：
You can get all feed of a user simply by query similar to:
SELECT * FROM users_feed as a WHERE a.user_id in < // select all
user_ids of loged in user //>）
SELECT * FROM users_feed as a WHERE a.user_id in ( < //select all user_ids of followers of loged in user// > )
（语法不跟随表
结构的追随者是不知道）
(Syntax not followed as table structure of followers is not known)
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