模式演进与兼容模式
学习 Avro 模式如何随时间演进，以及 Schema Registry 的兼容模式如何让生产者和消费者独立变更而不会相互破坏。
模式演进与兼容模式 是 CoddyKit 上的免费 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课时。 这是第 4 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Why Schemas Change
Real systems evolve: new fields are added, old ones deprecated. Schema evolution is the discipline of changing schemas without breaking existing producers or consumers.
The Compatibility Contract
Schema Registry enforces a compatibility mode on each subject. Before registering a new schema version, the registry checks it against existing versions and rejects breaking changes.
Backward Compatibility
BACKWARD (the default): new consumers can read data written by the previous schema.
- You may delete fields.
- You may add fields that have a default value.
Forward Compatibility
FORWARD: old consumers can read data written by the new schema.
- You may add fields.
- You may delete fields that have a default value.
Full Compatibility
FULL combines both: a change must be backward and forward compatible. The safest but most restrictive mode — only fields with defaults may be added or removed.
Adding a Field Safely
To add a field while keeping backward compatibility, give it a default so old data deserializes cleanly.
{
"name": "discount",
"type": "double",
"default": 0.0
}Setting Compatibility per Subject
You can configure compatibility globally or override it per subject via the registry REST API.
PUT /config/orders-value
{ "compatibility": "FULL" }Breaking Changes to Avoid
These changes break compatibility:
- Adding a required field without a default.
- Renaming a field (it is treated as delete plus add).
- Changing a field's type incompatibly.
Transitive Modes
Modes like BACKWARD_TRANSITIVE check the new schema against all prior versions, not just the latest — important when consumers may lag many versions behind.
Rollout Strategy
With BACKWARD compatibility, upgrade consumers first, then producers. With FORWARD, upgrade producers first. Knowing the mode dictates deployment order.
Putting It Together
Schema evolution lets independent teams move at their own pace. Choose a compatibility mode, always add new fields with defaults, and follow the matching deployment order.
Quick Check
Test your understanding of compatibility modes.
Recap
You learned schema evolution and compatibility.
- BACKWARD, FORWARD, and FULL define what changes are allowed.
- Add new fields with a
defaultto stay compatible. - Transitive modes check against all prior versions.
- Compatibility mode dictates producer/consumer upgrade order.
常见问题解答
「模式演进与兼容模式」课时是免费的吗？
是的 — 「模式演进与兼容模式」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课程的其余内容，请升级到 CoddyKit PRO。 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课程共包含 4 节课。
「模式演进与兼容模式」这节课中我会学到什么？
学习 Avro 模式如何随时间演进，以及 Schema Registry 的兼容模式如何让生产者和消费者独立变更而不会相互破坏。 你通过在浏览器中直接运行的动手代码来练习 Advanced Spring Boot 4: Event-Driven Architecture (Kafka)，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 4 节课，共 4 节。
「模式演进与兼容模式」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课中编写并运行代码吗？
能。每节 Advanced Spring Boot 4: Event-Driven Architecture (Kafka) 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。