设计模式以使cloudant上的文档过期

本文介绍了设计模式以使cloudant上的文档过期的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

因此，当删除文档时，元数据实际上会永久保留。对于像cloudant这样的托管服务，每月需要支付存储费用，我想彻底清除已删除的文档。

So when a document is deleted, the metadata is actually preserved forever. For a hosted service like cloudant, where storage costs every month, I instead would like to completely purge the deleted documents.

我读过某处关于设计模式的地方，您在其中使用 dbcopy ，以将文档放入当前数据库，然后定期删除过期的db。但是我找不到这篇文章，而且我不太了解数据库命名的工作原理。 cloudant客户端将如何始终知道当前数据库名称？

I read somewhere about a design pattern where you use dbcopy in a view to put the docs into a 'current' db then periodically delete the expired dbs. But I cant find the article, and I don't quite understand how database naming would work. How would the cloudant clients always know the 'current' database name?

推荐答案

Cloudant不公开_purge端点（宽松的一致性）

Cloudant does not expose the _purge endpoint (the loose consistency guarantees between the clustered nodes make purging tricky).

此问题最常见的解决方案是创建第二个数据库，并使用带有validate_document_update的复制，以便删除没有目标数据库中的现有条目将被拒绝。复制完成后（如果使用连续复制，则为最新状态），将您的应用程序切换为使用新数据库并删除旧数据库。当前无法重命名数据库，但是您可以使用指向当前数据库的虚拟主机。

The most common solution to this problem is to create a second database and use replication with a validate_document_update so that deleted documents with no existing entry in the target database are rejected. When replication is complete (or acceptably up-to-date if using continuous replication), switch your application to use the new database and delete the old one. There is currently no way to rename databases but you could use a virtual host which points to the "current" database.

我警告说，工作负载会产生很高的负担。删除：活动文档的比例通常是Cloudant中的反模式。我首先考虑是否可以更改文档模型来避免这种情况。

I'd caution that a workload which generates a high ratio of deleted:active documents is generally an anti-pattern in Cloudant. I would first consider whether you can change your document model to avoid it.