[BUG]: "'SequenceIterator' object is not iterable in file" in Hybrid Search

[diogocosta876]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I want to perform a weighted BM25 search and the milvus_client code is throwing an error

Currently using 2.5.4 python sdk and milvus standalone, I've posted the docker compose and python version below under "Software version"

This is my code for searching the indexes with BM25, that individually work but errors with hybrid_search:

index_params = MilvusClient.prepare_index_params()
index_params.add_index(
    field_name="sparse",
    index_type="SPARSE_INVERTED_INDEX",
    metric_type="BM25"
)

index_params.add_index(
    field_name="sparse2",
    index_type="SPARSE_INVERTED_INDEX",
    metric_type="BM25"
)

# Search parameters for sparse vector search
search_param_sparse = {
    "data": ["Who started AI research?"],  # Your search query
    "anns_field": "sparse",
    "param": {
        "metric_type": "BM25",
        "params": {}
    },
    "limit": 3
}
request_sparse = AnnSearchRequest(**search_param_sparse)

search_param_sparse2 = {
    "data": ["Who started AI research?"],  # Your search query
    "anns_field": "sparse2",
    "param": {
        "metric_type": "BM25",
        "params": {}
    },
    "limit": 3
}


request_sparse2 = AnnSearchRequest(**search_param_sparse2)
results = client.hybrid_search(
    collection_name="demo",
    reqs=[request_sparse, request_sparse2],
    ranker=WeightedRanker(0.7, 0.3),  # Give 70% weight to sparse search
    limit=3
)

Error Trace:

Traceback (most recent call last):
  File "<LOCAL-PATH>\test_milvus_bm25.py", line 145, in <module>
    results = client.hybrid_search(
        collection_name="demo",
    ...<2 lines>...
        limit=3
    )
  File "<LOCAL-PATH>\.venv\Lib\site-packages\pymilvus\milvus_client\milvus_client.py", line 359, in hybrid_search
    ret.append([hit.to_dict() for hit in hits])
                                         ^^^^
TypeError: 'SequenceIterator' object is not iterable

This is what I changed on milvus client code to make it work:
From:

      try:
            res = conn.hybrid_search(
                collection_name,
                reqs,
                ranker,
                limit=limit,
                partition_names=partition_names,
                output_fields=output_fields,
                timeout=timeout,
                **kwargs,
            )
        except Exception as ex:
            logger.error("Failed to hybrid search collection: %s", collection_name)
            raise ex from ex

        ret = []
        for hits in res:
            ret.append([hit.to_dict() for hit in hits])

        return ExtraList(ret, extra=construct_cost_extra(res.cost))

To:

        try:
            res = conn.hybrid_search(
                collection_name,
                reqs,
                ranker,
                limit=limit,
                partition_names=partition_names,
                output_fields=output_fields,
                timeout=timeout,
                **kwargs,
            )

        except Exception as ex:
            logger.error("Failed to hybrid search collection: %s", collection_name)
            raise ex from ex

        ret = []
        for hits in res:
            ret.append([hit.to_dict() for hit in list(hits)]) #added list() method

        return ExtraList(ret, extra=construct_cost_extra(res.cost))

And it now works without throwing the error.
Is any of my dependencies missmatching or is the hybrid search code on the client bricked for this version?

Steps To Reproduce

1. Perform a Hybrid Search (I wasn't able to perform it in any way I tried)

Software version

Milvus: 2.5.4
Server: ?
Client: Python SDK 2.5.4


Name: pymilvus
Version: 2.5.4
Summary: Python Sdk for Milvus


Docker Compose:

version: '3.5'

services:
  etcd:
    container_name: milvus-etcd
    image: quay.io/coreos/etcd:v3.5.5
    environment:
      - ETCD_AUTO_COMPACTION_MODE=revision
      - ETCD_AUTO_COMPACTION_RETENTION=1000
      - ETCD_QUOTA_BACKEND_BYTES=4294967296
      - ETCD_SNAPSHOT_COUNT=50000
    volumes:
      - ${DOCKER_VOLUME_DIRECTORY:-.}/volumes/etcd:/etcd
    command: etcd -advertise-client-urls=http://127.0.0.1:2379 -listen-client-urls http://0.0.0.0:2379 --data-dir /etcd
    healthcheck:
      test: ["CMD", "etcdctl", "endpoint", "health"]
      interval: 30s
      timeout: 20s
      retries: 3

  minio:
    container_name: milvus-minio
    image: minio/minio:RELEASE.2023-03-20T20-16-18Z
    environment:
      MINIO_ACCESS_KEY: minioadmin
      MINIO_SECRET_KEY: minioadmin
    ports:
      - "9001:9001"
      - "9000:9000"
    volumes:
      - ${DOCKER_VOLUME_DIRECTORY:-.}/volumes/minio:/minio_data
    command: minio server /minio_data --console-address ":9001"
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:9000/minio/health/live"]
      interval: 30s
      timeout: 20s
      retries: 3

  standalone:
    container_name: milvus-standalone
    image: milvusdb/milvus:v2.5.4
    command: ["milvus", "run", "standalone"]
    security_opt:
    - seccomp:unconfined
    environment:
      ETCD_ENDPOINTS: etcd:2379
      MINIO_ADDRESS: minio:9000
    volumes:
      - ./milvus.yaml:/milvus/configs/milvus.yaml
      - ${DOCKER_VOLUME_DIRECTORY:-.}/volumes/milvus:/var/lib/milvus
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:9091/healthz"]
      interval: 30s
      start_period: 90s
      timeout: 20s
      retries: 3
    ports:
      - "19530:19530"
      - "9091:9091"
    depends_on:
      - "etcd"
      - "minio"

  attu:
    container_name: milvus-attu
    image: zilliz/attu:v2.5.2
    environment:
      MILVUS_URL: standalone:19530
    ports:
      - "8009:3000"
    depends_on:
      - "standalone"

networks:
  default:
    name: milvus