docs/guide/xlang/row_format.md

---
title: Row Format
sidebar_position: 60
id: row_format
license: |
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
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---

Fory Row Format is a cache-friendly binary format designed for efficient random access and partial serialization. Unlike object graph serialization, row format allows you to read individual fields without deserializing the entire object.

## Features

- **Zero-Copy Random Access**: Read specific fields directly from binary data
- **Partial Serialization**: Skip unnecessary fields during serialization
- **Cross-Language Compatible**: Row format data can be shared between Java, Python, and C++
- **Apache Arrow Integration**: Convert row format to/from Arrow RecordBatch for analytics (Java/Python)

## Java

```java
public class Bar {
  String f1;
  List<Long> f2;
}

public class Foo {
  int f1;
  List<Integer> f2;
  Map<String, Integer> f3;
  List<Bar> f4;
}

RowEncoder<Foo> encoder = Encoders.bean(Foo.class);
Foo foo = new Foo();
foo.f1 = 10;
foo.f2 = IntStream.range(0, 1000000).boxed().collect(Collectors.toList());
foo.f3 = IntStream.range(0, 1000000).boxed().collect(Collectors.toMap(i -> "k"+i, i->i));
List<Bar> bars = new ArrayList<>(1000000);
for (int i = 0; i < 1000000; i++) {
  Bar bar = new Bar();
  bar.f1 = "s"+i;
  bar.f2 = LongStream.range(0, 10).boxed().collect(Collectors.toList());
  bars.add(bar);
}
foo.f4 = bars;
// Can be zero-copy read by Python
BinaryRow binaryRow = encoder.toRow(foo);
// Can be data from Python
Foo newFoo = encoder.fromRow(binaryRow);
// Zero-copy read List<Integer> f2
BinaryArray binaryArray2 = binaryRow.getArray(1);
// Zero-copy read List<Bar> f4
BinaryArray binaryArray4 = binaryRow.getArray(3);
// Zero-copy read 11th element of List<Bar> f4
BinaryRow barStruct = binaryArray4.getStruct(10);

// Zero-copy read 6th element of f2 of 11th element of List<Bar> f4
barStruct.getArray(1).getInt64(5);
RowEncoder<Bar> barEncoder = Encoders.bean(Bar.class);
// Deserialize part of data
Bar newBar = barEncoder.fromRow(barStruct);
Bar newBar2 = barEncoder.fromRow(binaryArray4.getStruct(20));
```

## Python

```python
@dataclass
class Bar:
    f1: str
    f2: List[pa.int64]
@dataclass
class Foo:
    f1: pa.int32
    f2: List[pa.int32]
    f3: Dict[str, pa.int32]
    f4: List[Bar]

encoder = pyfory.encoder(Foo)
foo = Foo(f1=10, f2=list(range(1000_000)),
         f3={f"k{i}": i for i in range(1000_000)},
         f4=[Bar(f1=f"s{i}", f2=list(range(10))) for i in range(1000_000)])
binary: bytes = encoder.to_row(foo).to_bytes()
print(f"start: {datetime.datetime.now()}")
foo_row = pyfory.RowData(encoder.schema, binary)
print(foo_row.f2[100000], foo_row.f4[100000].f1, foo_row.f4[200000].f2[5])
print(f"end: {datetime.datetime.now()}")

binary = pickle.dumps(foo)
print(f"pickle start: {datetime.datetime.now()}")
new_foo = pickle.loads(binary)
print(new_foo.f2[100000], new_foo.f4[100000].f1, new_foo.f4[200000].f2[5])
print(f"pickle end: {datetime.datetime.now()}")
```

## Apache Arrow Support

Fory Row Format supports automatic conversion from/to Arrow Table/RecordBatch for analytics workloads.

### Java

```java
Schema schema = TypeInference.inferSchema(BeanA.class);
ArrowWriter arrowWriter = ArrowUtils.createArrowWriter(schema);
Encoder<BeanA> encoder = Encoders.rowEncoder(BeanA.class);
for (int i = 0; i < 10; i++) {
  BeanA beanA = BeanA.createBeanA(2);
  arrowWriter.write(encoder.toRow(beanA));
}
return arrowWriter.finishAsRecordBatch();
```

### Python

```python
import pyfory
encoder = pyfory.encoder(Foo)
encoder.to_arrow_record_batch([foo] * 10000)
encoder.to_arrow_table([foo] * 10000)
```

## Support for Interface and Extension Types

Fory supports row format mapping for Java `interface` types and subclassed (`extends`) types, enabling more dynamic and flexible data schemas.

These enhancements were introduced in [#2243](https://github.com/apache/fory/pull/2243), [#2250](https://github.com/apache/fory/pull/2250), and [#2256](https://github.com/apache/fory/pull/2256).

### Example: Interface Mapping with RowEncoder

```java
public interface Animal {
  String speak();
}

public class Dog implements Animal {
  public String name;

  @Override
  public String speak() {
    return "Woof";
  }
}

// Encode and decode using RowEncoder with interface type
RowEncoder<Animal> encoder = Encoders.bean(Animal.class);
Dog dog = new Dog();
dog.name = "Bingo";
BinaryRow row = encoder.toRow(dog);
Animal decoded = encoder.fromRow(row);
System.out.println(decoded.speak()); // Woof
```

### Example: Extension Type with RowEncoder

```java
public class Parent {
    public String parentField;
}

public class Child extends Parent {
    public String childField;
}

// Encode and decode using RowEncoder with parent class type
RowEncoder<Parent> encoder = Encoders.bean(Parent.class);
Child child = new Child();
child.parentField = "Hello";
child.childField = "World";
BinaryRow row = encoder.toRow(child);
Parent decoded = encoder.fromRow(row);
```

## See Also

- [Row Format Specification](https://fory.apache.org/docs/next/specification/fory_row_format_spec) - Binary format details
- [Java Row Format Guide](../java/row-format.md) - Java-specific row format documentation
- [Python Row Format Guide](../python/row-format.md) - Python-specific row format documentation