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fix(java): support FixedSizeList for java LanceField #5509

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fix(java): support FixedSizeList for java LanceField #5509

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5 changes: 4 additions & 1 deletion java/lance-jni/src/schema.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,9 +39,11 @@ pub fn convert_to_java_field<'local>(
let name = env.new_string(&lance_field.name)?;
let children = convert_children_fields(env, lance_field)?;
let metadata = to_java_map(env, &lance_field.metadata)?;
let logical_type = env.new_string(lance_field.logical_type.to_string())?;
let arrow_type = convert_arrow_type(env, &lance_field.data_type())?;
let ctor_sig = "(IILjava/lang/String;".to_owned()
+ "ZLorg/apache/arrow/vector/types/pojo/ArrowType;"
+ "ZLjava/lang/String;"
+ "Lorg/apache/arrow/vector/types/pojo/ArrowType;"
+ "Lorg/apache/arrow/vector/types/pojo/DictionaryEncoding;"
+ "Ljava/util/Map;"
+ "Ljava/util/List;Z)V";
Expand All @@ -53,6 +55,7 @@ pub fn convert_to_java_field<'local>(
JValue::Int(lance_field.parent_id as jint),
JValue::Object(&JObject::from(name)),
JValue::Bool(lance_field.nullable as jboolean),
JValue::Object(&JObject::from(logical_type)),
JValue::Object(&arrow_type),
JValue::Object(&JObject::null()),
JValue::Object(&metadata),
Expand Down
130 changes: 130 additions & 0 deletions java/src/main/java/org/lance/schema/LanceField.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,11 +14,17 @@
package org.lance.schema;

import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableMap;
import org.apache.arrow.vector.types.DateUnit;
import org.apache.arrow.vector.types.FloatingPointPrecision;
import org.apache.arrow.vector.types.TimeUnit;
import org.apache.arrow.vector.types.pojo.ArrowType;
import org.apache.arrow.vector.types.pojo.DictionaryEncoding;
import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.FieldType;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Optional;
Expand All @@ -29,6 +35,7 @@ public class LanceField {
private final int parentId;
private final String name;
private final boolean nullable;
private final String logicalType;
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@majin1102 majin1102 Dec 17, 2025

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#4207 (comment)

Just a little context

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@fangbo fangbo Dec 17, 2025

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For lance vector data type, only the logicalType has FixedSizeList's element type, such as fixed_size_list:float:3.

So, when LanceField is converted to arrow Field , the FixedSizeList's children should be constructed from logicalType.

private final ArrowType type;
private final DictionaryEncoding dictionaryEncoding;
private final Map<String, String> metadata;
Expand All @@ -40,6 +47,7 @@ public class LanceField {
int parentId,
String name,
boolean nullable,
String logicalType,
ArrowType type,
DictionaryEncoding dictionaryEncoding,
Map<String, String> metadata,
Expand All @@ -49,6 +57,7 @@ public class LanceField {
this.parentId = parentId;
this.name = name;
this.nullable = nullable;
this.logicalType = logicalType;
this.type = type;
this.dictionaryEncoding = dictionaryEncoding;
this.metadata = metadata;
Expand All @@ -72,6 +81,10 @@ public boolean isNullable() {
return nullable;
}

public String getLogicalType() {
return logicalType;
}

public ArrowType getType() {
return type;
}
Expand All @@ -95,17 +108,134 @@ public boolean isUnenforcedPrimaryKey() {
public Field asArrowField() {
List<Field> arrowChildren =
children.stream().map(LanceField::asArrowField).collect(Collectors.toList());

if (type instanceof ArrowType.FixedSizeList) {
arrowChildren.addAll(childrenForFixedSizeList());
}

return new Field(
name, new FieldType(nullable, type, dictionaryEncoding, metadata), arrowChildren);
}

private List<Field> childrenForFixedSizeList() {
if (logicalType == null || logicalType.isEmpty()) {
return Collections.emptyList();
}

if (!(type instanceof ArrowType.FixedSizeList)) {
return Collections.emptyList();
}

if (!logicalType.startsWith("fixed_size_list:")) {
return Collections.emptyList();
}

String[] parts = logicalType.split(":");
if (parts.length < 3) {
throw new IllegalArgumentException("Unsupported logical type: " + logicalType);
}

String innerLogicalType =
Arrays.asList(parts).subList(1, parts.length - 1).stream().collect(Collectors.joining(":"));

Field itemField;
switch (innerLogicalType) {
case "lance.bfloat16":
itemField =
new Field(
"item",
new FieldType(
true,
new ArrowType.FixedSizeBinary(2),
null,
ImmutableMap.of(
"ARROW:extension:name", "lance.bfloat16",
"ARROW:extension:metadata", "")),
Collections.emptyList());
return Collections.singletonList(itemField);

default:
ArrowType elementType = arrowTypeFromLogicalType(innerLogicalType);
itemField =
new Field(
"item",
new FieldType(true, elementType, null, Collections.emptyMap()),
Collections.emptyList());
return Collections.singletonList(itemField);
}
}

private ArrowType arrowTypeFromLogicalType(String logicalType) {
switch (logicalType) {
case "null":
return ArrowType.Null.INSTANCE;
case "bool":
return ArrowType.Bool.INSTANCE;
case "int8":
return new ArrowType.Int(8, true);
case "uint8":
return new ArrowType.Int(8, false);
case "int16":
return new ArrowType.Int(16, true);
case "uint16":
return new ArrowType.Int(16, false);
case "int32":
return new ArrowType.Int(32, true);
case "uint32":
return new ArrowType.Int(32, false);
case "int64":
return new ArrowType.Int(64, true);
case "uint64":
return new ArrowType.Int(64, false);
case "halffloat":
return new ArrowType.FloatingPoint(FloatingPointPrecision.HALF);
case "float":
return new ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE);
case "double":
return new ArrowType.FloatingPoint(FloatingPointPrecision.DOUBLE);
case "string":
return ArrowType.Utf8.INSTANCE;
case "binary":
return ArrowType.Binary.INSTANCE;
case "large_string":
return ArrowType.LargeUtf8.INSTANCE;
case "large_binary":
case "blob":
case "json":
return ArrowType.LargeBinary.INSTANCE;
case "date32:day":
return new ArrowType.Date(DateUnit.DAY);
case "date64:ms":
return new ArrowType.Date(DateUnit.MILLISECOND);
case "time32:s":
return new ArrowType.Time(TimeUnit.SECOND, 32);
case "time32:ms":
return new ArrowType.Time(TimeUnit.MILLISECOND, 32);
case "time64:us":
return new ArrowType.Time(TimeUnit.MICROSECOND, 64);
case "time64:ns":
return new ArrowType.Time(TimeUnit.NANOSECOND, 64);
case "duration:s":
return new ArrowType.Duration(TimeUnit.SECOND);
case "duration:ms":
return new ArrowType.Duration(TimeUnit.MILLISECOND);
case "duration:us":
return new ArrowType.Duration(TimeUnit.MICROSECOND);
case "duration:ns":
return new ArrowType.Duration(TimeUnit.NANOSECOND);
default:
throw new IllegalArgumentException("Unsupported logical type: " + logicalType);
}
}

@Override
public String toString() {
return MoreObjects.toStringHelper(this)
.add("id", id)
.add("parentId", parentId)
.add("name", name)
.add("nullable", nullable)
.add("logicalType", logicalType)
.add("type", type)
.add("dictionaryEncoding", dictionaryEncoding)
.add("children", children)
Expand Down
27 changes: 26 additions & 1 deletion java/src/test/java/org/lance/TestUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import org.lance.fragment.FragmentUpdateResult;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import org.apache.arrow.c.ArrowArrayStream;
Expand Down Expand Up @@ -357,7 +358,31 @@ public static class ComplexTestDataset extends TestDataset {
FieldType.nullable(new ArrowType.Struct()),
Arrays.asList(
Field.nullable("field1", ArrowType.Utf8.INSTANCE),
Field.nullable("field2", new ArrowType.Int(16, true))))));
Field.nullable("field2", new ArrowType.Int(16, true)))),

// fixed size list type
new Field(
"fixed_size_list_col",
FieldType.nullable(new ArrowType.FixedSizeList(3)),
Collections.singletonList(Field.nullable("item", new ArrowType.Int(32, true)))),

// fixed bfloat16 list type
new Field(
"bfloat16_fixed_size_list_col",
FieldType.nullable(new ArrowType.FixedSizeList(3)),
Collections.singletonList(
new Field(
"item",
new FieldType(
true,
new ArrowType.FixedSizeBinary(2),
null,
ImmutableMap.of(
"ARROW:extension:name",
"lance.bfloat16",
"ARROW:extension:metadata",
"")),
Collections.emptyList())))));

public ComplexTestDataset(BufferAllocator allocator, String datasetPath) {
super(allocator, datasetPath);
Expand Down
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