Cherry pick partition key fix and example (#541)

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

client/insert.go

@@ -65,9 +65,7 @@ func (c *GrpcClient) Insert(ctx context.Context, collName string, partitionName
 		PartitionName:  partitionName,
 		FieldsData:     fieldsData,
 	}
-	if req.PartitionName == "" {
-		req.PartitionName = "_default" // use default partition
-	}
+
 	req.NumRows = uint32(rowSize)
 
 	resp, err := c.Service.Insert(ctx, req)

examples/partitionkey/main.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"context"
+	"log"
+	"math/rand"
+	"time"
+
+	"github.com/milvus-io/milvus-sdk-go/v2/client"
+	"github.com/milvus-io/milvus-sdk-go/v2/entity"
+)
+
+const (
+	milvusAddr     = `localhost:19530`
+	nEntities, dim = 10000, 128
+	collectionName = "hello_partition_key"
+
+	idCol, keyCol, embeddingCol = "ID", "key", "embeddings"
+	topK                        = 3
+)
+
+func main() {
+	ctx := context.Background()
+
+	log.Println("start connecting to Milvus")
+	c, err := client.NewClient(ctx, client.Config{
+		Address: milvusAddr,
+	})
+	if err != nil {
+		log.Fatalf("failed to connect to milvus, err: %v", err)
+	}
+	defer c.Close()
+
+	// delete collection if exists
+	has, err := c.HasCollection(ctx, collectionName)
+	if err != nil {
+		log.Fatalf("failed to check collection exists, err: %v", err)
+	}
+	if has {
+		c.DropCollection(ctx, collectionName)
+	}
+
+	// create collection
+	log.Printf("create collection `%s`\n", collectionName)
+	schema := entity.NewSchema().WithName(collectionName).WithDescription("hello_partition_key is the a demo to introduce the partition key related APIs").
+		WithField(entity.NewField().WithName(idCol).WithDataType(entity.FieldTypeInt64).WithIsPrimaryKey(true).WithIsAutoID(true)).
+		WithField(entity.NewField().WithName(keyCol).WithDataType(entity.FieldTypeInt64).WithIsPartitionKey(true)).
+		WithField(entity.NewField().WithName(embeddingCol).WithDataType(entity.FieldTypeFloatVector).WithDim(dim))
+
+	if err := c.CreateCollection(ctx, schema, entity.DefaultShardNumber, client.WithPartitionNum(32)); err != nil { // use default shard number
+		log.Fatalf("create collection failed, err: %v", err)
+	}
+
+	var keyList []int64
+	var embeddingList [][]float32
+	keyList = make([]int64, 0, nEntities)
+	embeddingList = make([][]float32, 0, nEntities)
+	for i := 0; i < nEntities; i++ {
+		keyList = append(keyList, rand.Int63()%512)
+	}
+	for i := 0; i < nEntities; i++ {
+		vec := make([]float32, 0, dim)
+		for j := 0; j < dim; j++ {
+			vec = append(vec, rand.Float32())
+		}
+		embeddingList = append(embeddingList, vec)
+	}
+	keyColData := entity.NewColumnInt64(keyCol, keyList)
+	embeddingColData := entity.NewColumnFloatVector(embeddingCol, dim, embeddingList)
+
+	log.Println("start to insert data into collection")
+
+	if _, err := c.Insert(ctx, collectionName, "", keyColData, embeddingColData); err != nil {
+		log.Fatalf("failed to insert random data into `%s`, err: %v", collectionName, err)
+	}
+
+	log.Println("insert data done, start to flush")
+
+	if err := c.Flush(ctx, collectionName, false); err != nil {
+		log.Fatalf("failed to flush data, err: %v", err)
+	}
+	log.Println("flush data done")
+
+	// build index
+	log.Println("start creating index HNSW")
+	idx, err := entity.NewIndexHNSW(entity.L2, 16, 256)
+	if err != nil {
+		log.Fatalf("failed to create ivf flat index, err: %v", err)
+	}
+	if err := c.CreateIndex(ctx, collectionName, embeddingCol, idx, false); err != nil {
+		log.Fatalf("failed to create index, err: %v", err)
+	}
+
+	log.Printf("build HNSW index done for collection `%s`\n", collectionName)
+	log.Printf("start to load collection `%s`\n", collectionName)
+
+	// load collection
+	if err := c.LoadCollection(ctx, collectionName, false); err != nil {
+		log.Fatalf("failed to load collection, err: %v", err)
+	}
+
+	log.Println("load collection done")
+
+	vec2search := []entity.Vector{
+		entity.FloatVector(embeddingList[len(embeddingList)-2]),
+		entity.FloatVector(embeddingList[len(embeddingList)-1]),
+	}
+	begin := time.Now()
+	sp, _ := entity.NewIndexHNSWSearchParam(30)
+	_, err = c.Search(ctx, collectionName, nil, "", []string{keyCol}, vec2search,
+		embeddingCol, entity.L2, topK, sp)
+	if err != nil {
+		log.Fatalf("failed to search collection, err: %v", err)
+	}
+
+	log.Printf("search `%s` done, latency %v\n", collectionName, time.Since(begin))
+
+	c.DropCollection(ctx, collectionName)
+}