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commit aaa88d4e6b3d9a493e713c48d9ddcef9b2ce3a34
Author: Zhanghao Chen <m...@outlook.com>
AuthorDate: Mon Apr 8 22:07:01 2024 +0800
[FLINK-34123][docs][type] Add doc for built-in serialization support for
Map, List, and Collection
---
.../serialization/types_serialization.md | 26 +++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git
a/docs/content/docs/dev/datastream/fault-tolerance/serialization/types_serialization.md
b/docs/content/docs/dev/datastream/fault-tolerance/serialization/types_serialization.md
index 0d4441f4d3f..766024ccd75 100644
---
a/docs/content/docs/dev/datastream/fault-tolerance/serialization/types_serialization.md
+++
b/docs/content/docs/dev/datastream/fault-tolerance/serialization/types_serialization.md
@@ -37,15 +37,16 @@ Flink places some restrictions on the type of elements that
can be in a DataStre
The reason for this is that the system analyzes the types to determine
efficient execution strategies.
-There are seven different categories of data types:
+There are eight different categories of data types:
1. **Java Tuples** and **Scala Case Classes**
2. **Java POJOs**
3. **Primitive Types**
-4. **Regular Classes**
-5. **Values**
-6. **Hadoop Writables**
-7. **Special Types**
+4. **Common Collection Types**
+5. **Regular Classes**
+6. **Values**
+7. **Hadoop Writables**
+8. **Special Types**
#### Tuples and Case Classes
@@ -167,6 +168,21 @@ input.keyBy(_.word)
Flink supports all Java and Scala primitive types such as `Integer`, `String`,
and `Double`.
+#### Common Collection Types
+
+Flink comes with dedicated serialization support for common Java collection
types, which is more efficient than going
+through a general purpose serialization framework by avoiding analysis and
serialization of the type metadata.
+Currently, only `Map`, `List`, `Set` and its super interface `Collection`
+are supported. To utilize it, you need to declare the collection type with:
+
+1. Concrete type arguments: e.g. `List<String>` but not `List`, `List<T>`, or
`List<?>`, as Flink needs them to dispatch
+ serialization of the element types.
+2. Interface types: e.g. `List<String>` but not `LinkedList<String>`, as Flink
does not preserve the underlying
+ implementation types across serialization.
+
+Other nonqualified collection types will be handled by Flink as general class
types. If the implementation types are
+also required to be preserved, you also need to register it with a custom
serializer.
+
#### General Class Types
Flink supports most Java and Scala classes (API and custom).
