默认情况下使用 uuid 时，Cassandra TimeUUID 泛滥文件描述符 [英] Cassandra TimeUUID flood file descriptor when use uuid in default

问题描述

我有 Cassandra 模型

I have Cassandra model as

import uuid
from cassandra.cqlengine import columns
from cassandra.cqlengine.models import Model

class MyModel(Model):
    ...
    ...
    created_at = columns.TimeUUID(primary_key=True,
                         clustering_order='DESC',
                         default=uuid.uuid1)
    ...
    ...

最近应用程序达到了uuid1 创建未关闭文件 - 达到文件描述符限制.我试图找到解决方案，但似乎我认为哪些选项可能不起作用

Recentrly app hit the uuid1 creation doesn't close files - hits file descriptor limit. I try to find the solution, but seems what options I think might be not work

• 用uuid4替换默认的uuid1，但是TimeUUID需要时间部分，只有uuid1提供
• 在检查 uuid1 和 uuid_from_time，两者看起来一样，所以也不解决问题.

• Replace uuid1 in default with uuid4, but TimeUUID need time part in it, and only uuid1 provide that.
• Relace uuid1 with cassandra.util.uuid_from_time(time.time()), when check the code for both uuid1 and uuid_from_time, both are looks same, so that also not solve the problem.

最后一个选项是用 Timestamp 类型替换 TimeUUID，但是这个 created_at 列是 primary_key 和 clustering_order，所以不知道我能不能做到.

Last option is to replace TimeUUID with Timestamp type, but this created_at column is primary_key and clustering_order, so dont know I can do that or not.

我的列族已经有 1,000,000 多条数据，所以我不能丢掉它们.

My column family has already 1,000,000+ data, so I cant just drop them.

我也想知道，用TimeUUID代替timestamp有什么好处?

I also want to know, what is the advantage of using TimeUUID instead of timestamp ?

推荐答案

您确定遇到了您链接的 libuuid 问题吗?您的代码片段显示了标准库 uuid，它可能没有这个问题.您的程序中是否可能存在不同的文件描述符泄漏?

Are you certain you're hitting the libuuid issue you linked? Your code snippet shows the standard library uuid, which probably doesn't have that issue. Is it possible there's a different file descriptor leak in your program?

如果是libuuid，最简单的方法是使用标准库实现.如果速度是您的主要关注点，您可能会考虑构建不同版本的 libuuid 以与 python-libuuid 一起使用.我很快就尝试了这个，并没有注意到任何文件描述符泄漏:http://www.ossp.org/pkg/lib/uuid/

If it is libuuid, the easiest course would be to use the standard library implementation. If speed is a major concern for you, you might look into building a different version of libuuid to use with python-libuuid. I tried this one quickly and didn't notice any file descriptors leaking: http://www.ossp.org/pkg/lib/uuid/

我也想知道，用TimeUUID代替timestamp有什么好处?

I also want to know, what is the advantage of using TimeUUID instead of timestamp ?

您将无法更改现有表上列的类型，但可以回答您的问题:TimeUUID 通常用于避免冲突，其中多个事件可以写入相同的时间戳值.

You won't be able to change the type of the column on your existing table, but to answer your question: TimeUUID is usually used to avoid collisions where multiple events could be written in the same timestamp value.

这篇关于默认情况下使用 uuid 时，Cassandra TimeUUID 泛滥文件描述符的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！