是否有（廉价）方法来检查实体是否存在？ [英] Is there a (cheap) way to check if a entity exists?

问题描述

我有一些密钥，我唯一想知道的是数据存储中是否有匹配的实体。目前我在做：

I have some keys and the only thing I want to know is if there is a matching entity in datastore. currently I'm doing:

entities = db.get(keys)
for entity in entities:
     if entity:
           # some stuff
     else:
           # some other stuff

虽然这有效，但我只需要传递一个布尔值，而不是entier对象。有没有办法让这一点的代码更便宜？

While this works, I just need a boolean to be passed, not the entier object. Is there a way to make this bit of code a bit cheaper?

推荐答案

比较你现在正在做什么的速度使用按键查询一次一个地查询密钥。如果没有明确的赢家，则只需要按键查询，因为它的成本更低。

Compare the speed of what you're doing now against querying the keys one-at-a-time using a keys-only query. If there isn't a clear winner, take the keys-only query, since it costs less.

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