[v2][BFloat16Vector]--The search return result is empty, but the query return is correct。

[yongpengli-z]

Milvus-version：v2.4.4 java-sdk：master-latest Search in BFloat16Vector collection，the result is empty.

package com.zilliz.milvustestv2.vectorOperation;

import com.google.common.collect.Lists;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import com.zilliz.milvustestv2.utils.MathUtil;
import io.milvus.client.MilvusServiceClient;
import io.milvus.param.ConnectParam;
import io.milvus.param.collection.FlushParam;
import io.milvus.v2.client.ConnectConfig;
import io.milvus.v2.client.MilvusClientV2;
import io.milvus.v2.common.ConsistencyLevel;
import io.milvus.v2.common.IndexParam;
import io.milvus.v2.service.collection.request.CreateCollectionReq;
import io.milvus.v2.service.collection.request.LoadCollectionReq;
import io.milvus.v2.service.index.request.CreateIndexReq;
import io.milvus.v2.service.vector.request.InsertReq;
import io.milvus.v2.service.vector.request.QueryReq;
import io.milvus.v2.service.vector.request.SearchReq;
import io.milvus.v2.service.vector.request.data.*;
import io.milvus.v2.service.vector.response.InsertResp;
import io.milvus.v2.service.vector.response.QueryResp;
import io.milvus.v2.service.vector.response.SearchResp;

import java.nio.ByteBuffer;
import java.util.*;

public class BF16SearchIssue {
    private static int dim = 128;
    private static String uri="http://10.102.9.177:19530";
    private static String collectionName = "bf16Collection";
    private static String pkName = "fieldInt64";
    private static String vectorName = "fieldBFloat16Vector";

    public static void main(String[] args) {
        // connect
        MilvusClientV2 milvusClientV2 = new MilvusClientV2(ConnectConfig.builder()
                .uri(uri)
                .token("root:Milvus")
                .secure(false)
                .connectTimeoutMs(5000L)
                .build());
        // create collection
        CreateCollectionReq.FieldSchema fieldInt64 = CreateCollectionReq.FieldSchema.builder()
                .autoID(false)
                .dataType(io.milvus.v2.common.DataType.Int64)
                .isPrimaryKey(true)
                .name(pkName)
                .build();
        CreateCollectionReq.FieldSchema fieldVector = CreateCollectionReq.FieldSchema.builder()
                .dataType(io.milvus.v2.common.DataType.BFloat16Vector)
                .isPrimaryKey(false)
                .dimension(dim)
                .name(vectorName)
                .build();
        List<CreateCollectionReq.FieldSchema> fieldSchemaList = new ArrayList<>();
        fieldSchemaList.add(fieldInt64);
        fieldSchemaList.add(fieldVector);
        CreateCollectionReq.CollectionSchema collectionSchema = CreateCollectionReq.CollectionSchema.builder()
                .fieldSchemaList(fieldSchemaList)
                .build();
        CreateCollectionReq createCollectionReq = CreateCollectionReq.builder()
                .collectionSchema(collectionSchema)
                .collectionName(collectionName)
                .enableDynamicField(false)
                .description("collection desc")
                .numShards(1)
                .build();
        milvusClientV2.createCollection(createCollectionReq);
        // create index
        Map<String,Object> extraParamMap=new HashMap<String,Object>(){{
            put("M", 16);
            put("efConstruction", 64);
        }};
        IndexParam indexParam = IndexParam.builder()
                .fieldName(vectorName)
                .indexType(IndexParam.IndexType.HNSW)
                .metricType(IndexParam.MetricType.L2)
                .extraParams(extraParamMap)
                .build();

        milvusClientV2.createIndex(CreateIndexReq.builder()
                .collectionName(collectionName)
                .indexParams(Collections.singletonList(indexParam))
                .build());
        // load
        milvusClientV2.loadCollection(LoadCollectionReq.builder().collectionName(collectionName).build());
        // insert
        List<JsonObject> jsonObjects = generateDefaultData(20000, dim);
        InsertResp insert = milvusClientV2.insert(InsertReq.builder().collectionName(collectionName).data(jsonObjects).build());
        System.out.println(insert);
        //query
        QueryResp query = milvusClientV2.query(QueryReq.builder()
                .collectionName(collectionName)
                .ids(Lists.newArrayList(1,10,99)).build());
        System.out.println("query:"+query.getQueryResults());
        // search
        List<BaseVector> data = providerBaseVector(1, dim);
        for (int i = 0; i < 10; i++) {
            SearchResp search = milvusClientV2.search(SearchReq.builder()
                    .collectionName(collectionName)
                    .outputFields(Lists.newArrayList("*"))
                    .consistencyLevel(ConsistencyLevel.STRONG)
                    .data(data)
                    .topK(10)
                    .build());
            System.out.println("first:"+search);
        }
        // use v1 flush
        MilvusServiceClient milvusClientV1 = new MilvusServiceClient(ConnectParam.newBuilder()
                .withUri(uri).build());
        milvusClientV1.flush(FlushParam.newBuilder().withCollectionNames(Lists.newArrayList(collectionName)).withSyncFlush(true).build());
        // search again
        for (int i = 0; i < 10; i++) {
            SearchResp search2 = milvusClientV2.search(SearchReq.builder()
                    .collectionName(collectionName)
                    .outputFields(Lists.newArrayList("*"))
                    .consistencyLevel(ConsistencyLevel.STRONG)
                    .data(data)
                    .topK(10)
                    .build());
            System.out.println("second:" + search2);
        }
    }

    public static short floatToBF16(float value) {
        int bits = Float.floatToIntBits(value);
        int sign = bits >>> 31;
        int exp = (bits >>> 23) & 0xFF;
        int mantissa = bits & 0x7FFFFF;

        if (exp == 0xFF) {
            // 处理无穷大和 NaN
            if (mantissa == 0) {
                return (short) ((sign << 15) | 0x7C00);  // 正负无穷
            } else {
                return (short) ((sign << 15) | 0x7C00 | (mantissa >>> 13));  // NaN
            }
        }

        exp -= 127;
        exp += 16;
        if (exp >= 0x1F) {
            // 处理溢出情况
            return (short) ((sign << 15) | 0x7C00);
        } else if (exp <= 0) {
            // 处理下溢情况
            return 0;
        }

        return (short) ((sign << 15) | (exp << 10) | (mantissa >>> 13));
    }
    public static ByteBuffer generateBF16Vector(int dim) {
        Random ran = new Random();
        float randomFloat;
        int byteCount = dim * 2;
        ByteBuffer vector = ByteBuffer.allocate(byteCount);
        for (int i = 0; i < dim; ++i) {
            do {
                randomFloat = ran.nextFloat();
            } while (Float.isInfinite(randomFloat));
            short halfFloatValue = MathUtil.floatToBF16(randomFloat);
            ByteBuffer buffer = ByteBuffer.allocate(2);
            buffer.putShort(halfFloatValue);
            buffer.flip();
            vector.put(buffer.get(0));
            vector.put(buffer.get(1));
        }
        return vector;
    }

    public static List<JsonObject> generateDefaultData(long num, int dim) {
        List<JsonObject> jsonList = new ArrayList<>();
        Random ran = new Random();
        Gson gson = new Gson();
        for (long i = 0; i < num; i++) {
            JsonObject row = new JsonObject();
            row.addProperty(pkName, i);
            row.add(vectorName, gson.toJsonTree(generateBF16Vector(dim).array()));
            jsonList.add(row);
        }
        return jsonList;
    }
    public static List<BaseVector> providerBaseVector(int nq, int dim) {
        List<BaseVector> data = new ArrayList<>();
        List<ByteBuffer> vectors = new ArrayList<>();
        for (int n = 0; n < nq; ++n) {
            vectors.add(generateBF16Vector(dim));
        }
        vectors.forEach(x -> {
            data.add(new BFloat16Vec(x));
        });

        return data;

    }
}

[yhmo]

Root cause: The generateBF16Vector() generates invalid bfloat16 data that the server could not compute. Milvus server doesn't have the ability to distinguish this kind of invalid bfloat16 data.

In the generateBF16Vector(), ByteBuffer should be LITTLE_ENDIAN

public static ByteBuffer generateBF16Vector(int dim) {
  ByteBuffer buffer = ByteBuffer.allocate(2);
  buffer.order(ByteOrder.LITTLE_ENDIAN);
  buffer.putShort(halfFloatValue);
  ......