[GitHub] [pulsar] sijie commented on a change in pull request #4841: [Doc] Add Schema Evolution and Compatibility section

[GitBox <gi...@apache.org>]

sijie commented on a change in pull request #4841: [Doc] Add Schema Evolution and Compatibility section
URL: https://github.com/apache/pulsar/pull/4841#discussion_r309487303
 
 

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 File path: site2/docs/schema-evolution-compatibility.md
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+---
+id: schema-evolution-compatibility
+title: Schema evolution and compatibility
+sidebar_label: Schema evolution and compatibility
+---
+
+## Schema evolution
+
+Pulsar schema is defined in a data structure called `SchemaInfo`. 
+
+Each `SchemaInfo` stored with a topic has a version. The version is used to manage the schema changes happening within a topic. 
+
+The message produced with `SchemaInfo` is tagged with a schema version. When a message is consumed by a Pulsar client, the Pulsar client can use the schema version to retrieve the corresponding `SchemaInfo` and use the correct schema information to deserialize data.
+
+### What is schema evolution?
+
+Schemas store the details of attributes and types. To satisfy new business requirements,  you need to update schemas inevitably over time, which is called **schema evolution**. 
+
+Any schema changes affect downstream consumers. Schema evolution ensures that the downstream consumers can seamlessly handle data encoded with both old schemas and new schemas. 
+
+### How Pulsar schema should evolve? 
+
+The answer is Pulsar schema compatibility check strategy. It determines how schema compares old schemas with new schemas in topics.
+
+For more information, see [Schema compatibility check strategy](#schema-compatibility-check-strategy).
+
 
 Review comment:
   That's correct.

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