NHibernate Lazy=“额外" [英] NHibernate Lazy="Extra"

问题描述

对lazy="extra" 到底能做什么有很好的解释吗?

Is there a good explanation out there on what exactly lazy="extra" is capable of?

我看过的所有帖子都只是重复这样一个事实，即它将对 MyObject.ItsCollection.Count 的引用转换为 select count(*) 查询(假设它们尚未加载).

All the posts I've seen all just repeat the fact that it turns references to MyObject.ItsCollection.Count into select count(*) queries (assuming they're not loaded already).

我想知道它是否具有更强大的功能，例如将 MyObject.ItsCollection.Any(o => o.Whatever == 5) 转换为 SELECT ...EXISTS 查询.

I'd like to know if it's capable of more robust things, like turning MyObject.ItsCollection.Any(o => o.Whatever == 5) into a SELECT ...EXISTS query.

文档的第 18.1 节仅涉及它.我不是 NH 开发人员，所以我无法真正试验它并观看 SQL Profiler，而无需做一些工作来设置所有内容；我只是在寻找某种描述此功能功能的参考资料.

Section 18.1 of the docs only touches on it. I'm not an NH developer, so I can't really experiment with it and watch SQL Profiler without doing a bit of work getting everything set up; I'm just looking for some sort of reference describing what this feature is capable of.

谢谢！

推荐答案

对于 2.x 版本，它仅用于将 collection.Count() 转换为 select countcode> 并且就我在源代码中看到的而言，它还允许构造 collection[5] 获取该特定实体(具有索引 5)，而不是对整个集合进行补水.

for version 2.x it is only used to translate a collection.Count() into a select count and as far as i can see in the source, it will also allow the construct collection[5] to fetch that particular entity (with index 5) instead of hydrating the whole collection.

对于 3.x 版，我在发行说明中没有看到任何相关内容

For version 3.x i didn't see anything related in the release notes

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