CouchDB如何计算序列ID（seq） [英] How does CouchDB calculate the Sequence Id (seq)

问题描述

我正在源存储库中寻找伪代码或实际代码（ https://github.com/ apache / couchdb ），定义CouchDB如何计算 seq 值。

在docs： http://docs.couchdb.org/en/2.2。 0 / intro / overview.html 表示：

对数据库实例的每次更新都会产生一个新的序号。

但是它没有涉及到。我认为这可能与实现有关，请查看复制协议文档中的内容：

序列ID：
变更Feed提供的ID。它必须是渐进的，但可能不总是整数。

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  CouchDB如何计算修订号 
解决方案
您可以找到此处有关更改序列内部的一些信息
 
 
 
序列号反映了集群陈述文档更新序列，此信息被编码为序列号。 
 
 
 
序列号的数字部分是每个群集节点中文档更新序列的总和。 
 
 
 
序列号的第二部分是base64编码的字符串，其中包含每个群集节点中的更新序列信息。
 
I am looking for pseudo code or the actual code in the source repository (https://github.com/apache/couchdb) defining how CouchDB calculates the seq value.

Reviewing the technical overview in the docs: http://docs.couchdb.org/en/2.2.0/intro/overview.html it says:

  
Each update to a database instance generates a new sequential number.
But it doesn't go into how. I think that it may be implementation dependent, looking at the replication protocol docs it states:

  
Sequence ID:
  An ID provided by the Changes Feed. It MUST be incremental, but MAY NOT always be an integer.


 1-g1AAAAIreJyVkEsKwjAURZ-toI5cgq5A0sQ0OrI70XyppcaRY92J7kR3ojupaSPUUgotgRd4yTlwbw4A0zRUMLdnpaMkwmyF3Ily9xBwEIuiKLI05KOTW0wkV4rruP29UyGWbordzwKVxWBNOGMKZhertDlarbr5pOT3DV4gudUC9-MPJX9tpEAYx4TQASns2E24ucuJ7rXJSL1BbEgf3vTwpmedCZkYa7Pulck7Xt7x_usFU2aIHOD4eEfVTVA5KMGUkqhNZV-8_o5i
This questions is somewhat related in that it's asking how it calculates another component of a document, the rev:

How does CouchDB calculate the Revision number
解决方案
You can find here some information about the change sequence internals 

The sequence number reflects the cluster state for a document update sequence, this information is encoded into the sequence number. 

The numeric part of the sequence number is the sum of the update sequences of a document in each of the cluster nodes. 

The second part of the sequence number is a base64 encoded string with the update sequence information in each of the cluster nodes.

                        
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