Search()

This operation performs an approximate nearest neighbor (ANN) search on a specified collection. You can use NewSearchOption for vector-based search or NewSearchByIDsOption to search by primary key IDs.

func (c *Client) Search(ctx context.Context, option SearchOption, callOptions ...grpc.CallOption) ([]ResultSet, error)

Request Syntax

Vector search:

option := milvusclient.NewSearchOption(collectionName, limit, vectors).
    WithPartitions(partitionNames).
    WithFilter(expr).
    WithTemplateParam(key, val).
    WithOffset(offset).
    WithOutputFields(fieldNames).
    WithConsistencyLevel(consistencyLevel).
    WithANNSField(annsField).
    WithGroupByField(groupByField).
    WithGroupSize(groupSize).
    WithStrictGroupSize(strictGroupSize).
    WithIgnoreGrowing(ignoreGrowing).
    WithAnnParam(ap).
    WithSearchParam(key, value).
    WithFunctionReranker(fr)

resultSets, err := cli.Search(ctx, option)

Search by primary key IDs:

option := milvusclient.NewSearchByIDsOption(collectionName, limit, ids).
    WithPartitions(partitionNames).
    WithFilter(expr).
    WithOutputFields(fieldNames)

resultSets, err := cli.Search(ctx, option)

PARAMETERS:

• option (SearchOption) -

  The search options. Use NewSearchOption for vector search or NewSearchByIDsOption for PK-based search.

BUILDER METHODS:

• NewSearchOption(collectionName string, limit int, vectors []entity.Vector) This creates a search option for vector-based ANN search.

• NewSearchByIDsOption(collectionName string, limit int, ids column.Column) This creates a search option to find entities by their primary key IDs.

• WithPartitions(partitionNames ...string) This restricts the search to the specified partition names.

• WithFilter(expr string) This applies a boolean expression filter to the search results.

• WithTemplateParam(key string, val any) This sets a template parameter for expression evaluation.

• WithOffset(offset int) This sets the number of results to skip before returning matches.

• WithOutputFields(fieldNames ...string) This specifies which fields to return in the result sets.

• WithConsistencyLevel(consistencyLevel entity.ConsistencyLevel) This sets the consistency level for the search.

• WithANNSField(annsField string) This specifies the vector field to search on when a collection has multiple vector fields.

• WithGroupByField(groupByField string) This groups search results by the specified field.

• WithGroupSize(groupSize int) This sets the number of results to return per group when grouping is enabled.

• WithStrictGroupSize(strictGroupSize bool) This enforces strict group size limits.

• WithIgnoreGrowing(ignoreGrowing bool) This ignores growing segments during the search.

• WithAnnParam(ap index.AnnParam) This sets the approximate nearest neighbor search parameters (e.g., nprobe, ef).

• WithSearchParam(key, value string) This sets a custom search parameter key-value pair.

• WithFunctionReranker(fr *entity.Function) This applies a function-based reranker to the search results.

RETURN TYPE:

[]ResultSet, error

RETURNS:

The search or query results containing matched entities with scores and fields. Returns an error if the operation fails.

EXCEPTIONS:

• error

  Check err != nil for failure details.

Example

import (
    "context"
    "log"

    "github.com/milvus-io/milvus/client/v2/entity"
    "github.com/milvus-io/milvus/client/v2/milvusclient"
)

ctx, cancel := context.WithCancel(context.Background())
defer cancel()

milvusAddr := "127.0.0.1:19530"
token := "root:Milvus"

cli, err := milvusclient.New(ctx, &milvusclient.ClientConfig{
    Address: milvusAddr,
    APIKey:  token,
})
if err != nil {
    log.Fatal("failed to connect to milvus server: ", err.Error())
}

defer cli.Close(ctx)

queryVector := []float32{0.3580376395471989, -0.6023495712049978, 0.18414012509913835, -0.26286205330961354, 0.9029438446296592}

resultSets, err := cli.Search(ctx, milvusclient.NewSearchOption(
    "quick_setup", // collectionName
    3,             // limit
    []entity.Vector{entity.FloatVector(queryVector)},
))
if err != nil {
    log.Fatal("failed to perform basic ANN search collection: ", err.Error())
}

for _, resultSet := range resultSets {
    log.Println("IDs: ", resultSet.IDs)
    log.Println("Scores: ", resultSet.Scores)
}