这是另一个 Google App Engine 数据存储问题。
假设我的应用程序跟踪一群老鼠以及它们吃了多少奶酪。每个Rat 实体都有一系列Meal 实体——每个实体跟踪老鼠何时进食以及吃了多少片奶酪（slices 属性）。每只Rat还有一个total_slices属性，每当记录新的膳食时该属性都会更新。
每当我需要知道总数时，是否应该放弃 total_slices 属性，转而简单地将每份 Meal 的 slices 加起来？数据存储文档称查询很便宜，而高频更新实体是有问题的（谷歌将“高频”定义为以持续的速率每秒更新一次实体以上）。因此，如果我有一些非常贪婪的老鼠，每秒进食不止一次，那么当我更新 Rat 的 total_slices 时，我就会冒着超时的风险。
对于如何最好地设计这个场景有什么建议吗？
This is another Google App Engine Datastore question.
Let’s say my app tracks a bunch of rats and how much cheese they’ve eaten. Each Rat entity has a series of Meal entities -- each tracks when the rat ate and how many slices of cheese (slices property). Each Rat also has a total_slices property that is updated whenever a new meal is logged.
Should I abandon the total_slices property in favor of simply adding up the slices of each Meal whenever I need to know the total? The Datastore documentation says that queries are cheap, while updating an entity at a high frequency is problematic (Google defines “high frequency” as updating an entity more than once a second at a sustained rate). So if I have some really voracious rats that feast more than once a second, I’m risking a timeout when I update the Rat’s total_slices.
Any suggestions how to best design this scenario?
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您的问题包含两个单独的问题：
1。您是否应该将
total_slices反规范化为Rat实体？要回答这个问题，您必须分析应用程序的数据访问模式。例如：
Rat获取total_slices共同任务？
按
total_slices列出或排序Rats？餐加起来仍然是多年数据后的高效
已经积累了？
2.如果您的实体需要更新速度超过 1 秒，您会在 GAE 中做什么？
使用 分片计数器。
There are two separate issues wrapped up in your question:
1. Should you de-normalize
total_slicesto theRatentity?To answer this you must analyze the data access patterns of your application. For example:
total_slicesfor aRatacommon task?
list or sort
Ratsbytotal_slices?Mealstill beefficient after several years of data
have accumulated?
2. What do you do in GAE if you have an entity that needs to be updated more than 1/sec?
Use a Sharded Counter.