PostgreSQL具有递归性能 [英] PostgreSQL WITH RECURSIVE performance

问题描述

我有一个简单的问题。

I have a simple question. Somehow I was unable to find a definitive answer.

在PostgreSQL中优化了语法的语法是什么？我的意思是：这仅仅是一系列非递归查询的语法糖，还是它的复杂语义整体上得到了优化，而仅仅是一个语句。后续问题-可以优化这种语法多少？当然，最欢迎提供有关此问题的一些具体数据。

How much is WITH RECURSIVE syntax optimized in PostgreSQL? By that I mean: is it merely a syntactic sugar for a series of non recursive queries, OR is it more of a single statement that despite its complicated semantics has been optimized as a whole. A follow-up question - just about how much is it possible to optimize this kind of syntax? Of course some concrete data on the matter is most welcome.

推荐答案

我的经验是，它确实得到了很好的优化。

My experience is that it is indeed very well optimized.

查看由EXPLAIN ANALYZE生成的您的查询的执行计划，您将看到它的实际成本是多少（然后进行比较）一个自写的递归函数）

Check out the execution plan for your query generated by EXPLAIN ANALYZE and you'll see how "costly" it really is (and then compare that e.g. to a self written recursive function)

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