祖先在谷歌应用引擎数据存储中意味着什么

问题描述

任何人都可以告诉或定义更多什么是祖先，并举例说明它的用途？我无法理解它的真实含义。

参考：

感谢。

解决方案

只存在于祖先后裔群组中。等同地，在我刚刚提供的URL处引用文档，

和一个实体组，根据中定义：

仅仅是父母的传递闭包 - 即给定一个实体，它的祖先是，它的父母，父母的父母等等。

Can anyone tell or define more what is "ancestor" and give an example on it and also what it is for? I just can't grasp what it really is.

Reference: http://code.google.com/appengine/docs/python/datastore/queryclass.html#Query_ancestor

Thanks.

解决方案

Transactions in GAE only exist within ancestor-descendant groups. Equivalently, quoting the docs at the URL I just gave,

and an "entity group", per this page in the docs, are defined by:

"Ancestor" is just the transitive closure of "parent" -- i.e., given an entity, its ancestors are, its parent, its parent's parent, and so forth.

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