luoyuxia commented on issue #1569:
URL: https://github.com/apache/fluss/issues/1569#issuecomment-3213932870
We should have a better way to write to lance
```
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* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
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* See the License for the specific language governing permissions and
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package com.alibaba.fluss.lake.lance.tiering;
import org.apache.arrow.memory.RootAllocator;
import org.apache.arrow.vector.Float8Vector;
import org.apache.arrow.vector.IntVector;
import org.apache.arrow.vector.VarCharVector;
import org.apache.arrow.vector.VectorSchemaRoot;
import org.apache.arrow.vector.ipc.ArrowStreamReader;
import org.apache.arrow.vector.ipc.ArrowStreamWriter;
import org.apache.arrow.vector.types.FloatingPointPrecision;
import org.apache.arrow.vector.types.pojo.ArrowType;
import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.FieldType;
import org.apache.arrow.vector.types.pojo.Schema;
import org.junit.jupiter.api.Test;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
class LanceTest {
public static ArrowStreamReader createArrowStreamReader(List<Object[]>
data)
throws IOException {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
try (RootAllocator allocator = new RootAllocator(Long.MAX_VALUE)) {
Schema schema = createSchema();
try (VectorSchemaRoot root = VectorSchemaRoot.create(schema,
allocator)) {
ArrowStreamWriter writer = new ArrowStreamWriter(root, null,
outputStream);
writer.start();
for (int batchNum = 0; batchNum < 5; batchNum++) {
writeBatchToStream(root, data);
writer.writeBatch();
}
writer.end();
}
}
// Create ArrowStreamReader from the generated data
byte[] arrowData = outputStream.toByteArray();
ByteArrayInputStream inputStream = new
ByteArrayInputStream(arrowData);
return new ArrowStreamReader(inputStream, new
RootAllocator(Long.MAX_VALUE));
}
private static Schema createSchema() {
return new Schema(
Arrays.asList(
new Field(
"id", new FieldType(true, new
ArrowType.Int(32, true), null), null),
new Field("name", new FieldType(true, new
ArrowType.Utf8(), null), null),
new Field(
"age",
new FieldType(true, new ArrowType.Int(32,
true), null),
null),
new Field(
"salary",
new FieldType(
true,
new
ArrowType.FloatingPoint(FloatingPointPrecision.DOUBLE),
null),
null)));
}
private static void writeBatchToStream(VectorSchemaRoot root,
List<Object[]> data) {
root.clear();
IntVector idVector = (IntVector) root.getVector("id");
VarCharVector nameVector = (VarCharVector) root.getVector("name");
IntVector ageVector = (IntVector) root.getVector("age");
Float8Vector salaryVector = (Float8Vector) root.getVector("salary");
int batchSize = data.size();
// Allocate memory
idVector.allocateNew(batchSize);
nameVector.allocateNew(batchSize);
ageVector.allocateNew(batchSize);
salaryVector.allocateNew(batchSize);
// Fill data
for (int i = 0; i < batchSize; i++) {
Object[] row = data.get(i);
idVector.set(i, (Integer) row[0]);
nameVector.setSafe(i, ((String) row[1]).getBytes());
ageVector.set(i, (Integer) row[2]);
salaryVector.set(i, (Double) row[3]);
}
// Set value counts
idVector.setValueCount(batchSize);
nameVector.setValueCount(batchSize);
ageVector.setValueCount(batchSize);
salaryVector.setValueCount(batchSize);
root.setRowCount(batchSize);
}
@Test
void testLance() throws Exception {
List<Object[]> data =
Arrays.asList(
new Object[] {1, "John Doe", 10, 85.5},
new Object[] {2, "Jane Smith", 12, 92.0},
new Object[] {3, "Bob Johnson", 23, 78.5});
int batchCount = 0;
int totalRowsRead = 0;
try (ArrowStreamReader arrowStreamReader =
createArrowStreamReader(data)) {
while (arrowStreamReader.loadNextBatch()) {
batchCount++;
VectorSchemaRoot root =
arrowStreamReader.getVectorSchemaRoot();
totalRowsRead += root.getRowCount();
assertThat(root.getRowCount()).isEqualTo(data.size());
// Verify the content of the current batch
for (int i = 0; i < root.getRowCount(); i++) {
Object[] expectedRow = data.get(i);
assertThat(root.getVector("id").getObject(i)).isEqualTo(expectedRow[0]);
assertThat(root.getVector("name").getObject(i).toString())
.isEqualTo(expectedRow[1]);
assertThat(root.getVector("age").getObject(i)).isEqualTo(expectedRow[2]);
assertThat(root.getVector("salary").getObject(i)).isEqualTo(expectedRow[3]);
}
}
}
// Assert that we read the correct number of batches and total rows.
assertThat(batchCount).isEqualTo(5);
assertThat(totalRowsRead).isEqualTo(15);
}
}
```
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