Google App Engine Datastore 和其他 NoSQL 数据库的无架构设计指南 [英] Schema-less design guidelines for Google App Engine Datastore and other NoSQL DBs

问题描述

来自关系数据库背景，我相信很多其他人都是，我正在寻找一些可靠的指南，用于在 Google App Engine 上设置/设计我的数据存储.人们有什么好的经验法则来设置这些无模式的数据存储吗?我了解一些基础知识，例如非规范化，因为您不能进行联接，但我想知道人们还有什么其他建议.

Coming from a relational database background, as I'm sure many others are, I'm looking for some solid guidelines for setting up / designing my datastore on Google App Engine. Are there any good rules of thumb people have for setting up these kinds of schema-less data stores? I understand some of the basics such as denormalizing since you can't do joins, but I was wondering what other recommendations people had.

我正在处理的一个特别简单的示例涉及存储搜索及其结果.例如，我使用 Python 在我的 Google App Engine 应用中定义了以下两个模型:

The particular simple example I am working with concerns storing searches and their results. For example I have the following two models defined in my Google App Engine app using Python:

class Search(db.Model):
    who = db.StringProperty()
    what = db.StringProperty()
    where = db.StringProperty()

    createDate = db.DateTimeProperty(auto_now_add=True)

class SearchResult(db.Model):
    title = db.StringProperty()
    content = db.StringProperty()

    who = db.StringProperty()
    what = db.StringProperty()
    where = db.StringProperty()

    createDate = db.DateTimeProperty(auto_now_add=True)

为了非规范化，我在模型之间复制了一堆属性，因为我无法将 Search 和 SearchResult 连接在一起.这有意义吗?或者我应该在 SearchResult 模型中存储一个搜索 ID，并在我从数据存储中检索它们时有效地加入"代码中的两个模型?请记住，这是一个简单的例子.两种模型都会有更多的属性，而我现在正在处理这个问题的方式，我会将我放在 Search 模型中的任何属性也放在 SearchResult 模型中.

I'm duplicating a bunch of properties between the models for the sake of denormalization since I can't join Search and SearchResult together. Does this make sense? Or should I store a search ID in the SearchResult model and effectively "join" the two models in code when I retrieve them from the datastore? Please keep in mind that this is a simple example. Both models will have a lot more properties and the way I'm approaching this right now, I would put any property I put in the Search model in the SearchResult model as well.

推荐答案

如果 SearchResult 和 Search.如果 SearchResult 应该引用 Search，请保留 ReferenceProperty 指向搜索.这基本上是在模型中存储了相关的Search的Key.

Don't duplicate the properties if they'll always be the same between the SearchResult and a Search. If a SearchResult should have a reference to a Search, keep a ReferenceProperty pointing to the Search. This basically stores the related Search's Key in the model.

class SearchResult(db.Model):
    search = db.ReferenceProperty(Search, required=True)
    # other stuff...

我还强烈建议您观看一些上次的 App Engine 视频一年的 Google I/O(以及来自 2008)，尤其是 这个，作者 Brett Slatkin，以及这个 作者:Ryan Barrett.如果你有时间，它们都是非常有用的视频，但我发现这两个特别棒.

I also highly recommend you watch some of the App Engine videos from last year's Google I/O (and from 2008), in particular this one by Brett Slatkin, and this one by Ryan Barrett. They're all pretty helpful videos if you have the time, but I found those two in particular to be really great.

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