多租户指南：优势与挑战
本文介绍多租户架构的基本概念、数据隔离方案、共享带来的噪声邻居问题、爆炸半径及租户上下文的重要性。
中文处理结果
每个为多个客户构建应用的软件公司都必须回答这个问题：
每个客户应该获得系统的独立副本，还是所有客户共享同一系统？
为每个客户运行专用副本很容易理解，但随着每位新客户的加入，维护数百个独立副本的成本不断增加。另一方面，让所有客户共享一个系统的成本要低得多。这就是为什么我们日常使用的大多数软件都是为共享而不是复制而构建的。此类系统被称为多租户系统，其中每个客户都是与其他租户共享资源的租户。
然而，共享也正是困难开始的地方。
一旦许多客户依赖同一个数据库、同一批服务器和同一批后台任务，他们的命运就联系在一起了。例如，一个客户运行重报告可能会拖慢所有人的服务。一次错误的部署可能同时影响所有客户，而不仅仅是该客户。最严重的风险是数据泄露，即一个客户看到属于另一个客户的数据。所有这些情况都必须由多租户系统主动处理。
在本文中，我们将从基础开始理解多租户架构，以及它的各种优势和挑战。以下是我们要介绍的内容的快速概述：
- 租户到底是什么。
- 每个客户的数据可以物理存在于何处，从一组共享表到独立的数据库，以及每个选项的成本。
- 为什么在隔离和共享之间的相同选择也包括计算层及更上层，而不仅仅是数据库。
- 噪声邻居问题，以及为什么共享会影响公平性并迫使团队通过配额和限制来重建公平性。
- 爆炸半径在此类架构中的作用。
- 贯穿系统每个部分的租户上下文概念。
租户与用户
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原始正文摘录
A Guide to Multi-Tenancy: Benefits and Challenges
Every software company that builds an application serving more than one customer has to answer this question.
Should each customer get a separate copy of the system, or should they all share one?
Running a dedicated copy per customer is easy to reason about, but the cost of maintaining hundreds of separate copies increases with every new customer. On the other hand, sharing a single system across all customers is far cheaper. This is why most of the software we use every day is built to be shared rather than duplicated. Such systems are known as multi-tenant systems, where each customer is a tenant that shares resources with other tenants.
However, sharing is also where the difficulty begins.
Once many customers rely on the same database, the same servers, and the same background jobs, their fortunes become linked. For example, one customer running a heavy report can slow the service for everyone alongside them. A single faulty deployment can impact all of them at once instead of just the customer. And the most serious risk is around data leaks, where one customer is shown data that belongs to another. All of these situations have to be actively handled by a multi-tenant system.
In this article, we will understand multi-tenant architecture from the basics, along with its various benefits and challenges. Here’s a quick overview of what we will cover:
- What a tenant really is.
- Where each customer’s data can physically live, from one shared set of tables to a database of its own, and what each of those options costs.
- Why the same choice between isolating and sharing also includes the compute layer and beyond, not only in the database.
- The noisy neighbor problem, and why sharing can impact fairness and force a team to rebuild it with quotas and limits.
- The role of blast radius in such an architecture.
- The concept of tenant context that runs through every part of the system.
Tenants and Users
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