# LoadPartitions()

This operation loads the data of specific partitions in one collection into query nodes.

```cpp
Status LoadPartitions(const LoadPartitionsRequest& request)
```

## Request Syntax

```cpp
auto request = LoadPartitionsRequest()
    .WithDatabaseName(db_name)
    .WithCollectionName(collection_name)
    .WithPartitionNames(partition_names)
    .WithSync(sync)
    .WithReplicaNum(replica_num)
    .WithTimeoutMs(timeout_ms)
    .WithRefresh(refresh)
    .WithLoadFields(load_fields)
    .WithSkipDynamicField(skip_dynamic_field)
    .WithTargetResourceGroups(target_resource_groups);
```

**REQUEST METHODS:**

- `WithDatabaseName(const std::string& db_name)`

    Sets the target database name. The default database applies if it is empty.

- `WithCollectionName(const std::string& collection_name)`

    Sets the name of the collection.

- `WithPartitionNames(const std::set<std::string>& partition_names)`

    Sets the names of the partitions.

- `AddPartitionName(const std::string& partition_name)`

    Adds a partition to be loaded.

- `WithSync(bool sync)`

    Sets the sync mode. The default value is **True**. 

    - **True**: wait the collection to be fully loaded.

    - **False**: return immediately no matter the collection is fully loaded or not.

- `WithReplicaNum(int64_t replica_num)`

    Sets the number of replicas.

- `WithTimeoutMs(int64_t timeout_ms)`

    Sets the timeout in milliseconds. The default value is 60000 ms. This parameter only works when this operation works in sync mode. 

    If `WaitFlushedMs` is set to 0, this operation repeatedly calls `GetLoadingProgress()` to check the loading state until the collection is fully loaded into memory. If `WaitFlushedMs` is greater than 0, this operation will break the loop after a specified period of time and return a status indicating a timeout.

- `WithRefresh(bool refresh)`

    Sets the refresh option. This parameter takes effect when new segments are generated by the bulk import interface. 

    - **True**: Loads newly generated segments from the bulk import interface.

    - **False**: Ignores newly generated segments from the bulk import interface.

- `WithLoadFields(const std::set<std::string>& load_fields)`

    Sets the names of the fields to load.

- `AddLoadField(const std::string& load_field)`

    Adds the name of a field to load.

- `WithSkipDynamicField(bool skip_dynamic_field)`

    Sets whether to skip the dynamic field option.

- `WithTargetResourceGroups(const std::set<std::string>& target_resource_groups)`

    Sets the target resource groups. If it is empty, the partition data will be loaded into the default resource group.

- `AddTargetResourceGroups(const std::string& target_resource_group)`

    Adds a target resource group.

**RETURNS:**

*Status*

Check `status.IsOk()` to confirm success.

**EXCEPTIONS:**

- **StatusCode**

    Check `status.Code()` and `status.Message()` for error details.

## Example

```cpp
#include "milvus/MilvusClientV2.h"
auto client = milvus::MilvusClientV2::Create();

milvus::ConnectParam connect_param{"http://localhost:19530", "root:Milvus"};
auto status = client->Connect(connect_param);
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}

status = client->LoadPartitions(
    milvus::LoadPartitionsRequest()
        .WithCollectionName("my_collection")
        .AddPartitionName("partition_1")
        .AddPartitionName("partition_2")
        .WithSync(true));
if (!status.IsOk()) {
    std::cout << status.Message() << std::endl;
}
```