GrpcRequestTask.cpp

/*******************************************************************************
* Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
* Unauthorized copying of this file, via any medium is strictly prohibited.
* Proprietary and confidential.
******************************************************************************/
#include "GrpcRequestTask.h"
#include "../ServerConfig.h"
#include "utils/CommonUtil.h"
#include "utils/Log.h"
#include "utils/TimeRecorder.h"
#include "utils/ValidationUtil.h"
#include "../DBWrapper.h"
#include "version.h"
#include "GrpcMilvusServer.h"

#include "src/server/Server.h"

namespace zilliz {
namespace milvus {
namespace server {
namespace grpc {

static const char *DQL_TASK_GROUP = "dql";
static const char *DDL_DML_TASK_GROUP = "ddl_dml";
static const char *PING_TASK_GROUP = "ping";

using DB_META = zilliz::milvus::engine::meta::Meta;
using DB_DATE = zilliz::milvus::engine::meta::DateT;

namespace {
    engine::EngineType EngineType(int type) {
        static std::map<int, engine::EngineType> map_type = {
                {0, engine::EngineType::INVALID},
                {1, engine::EngineType::FAISS_IDMAP},
                {2, engine::EngineType::FAISS_IVFFLAT},
                {3, engine::EngineType::FAISS_IVFSQ8},
        };

        if (map_type.find(type) == map_type.end()) {
            return engine::EngineType::INVALID;
        }

        return map_type[type];
    }

    int IndexType(engine::EngineType type) {
        static std::map<engine::EngineType, int> map_type = {
                {engine::EngineType::INVALID,       0},
                {engine::EngineType::FAISS_IDMAP,   1},
                {engine::EngineType::FAISS_IVFFLAT, 2},
                {engine::EngineType::FAISS_IVFSQ8,  3},
        };

        if (map_type.find(type) == map_type.end()) {
            return 0;
        }

        return map_type[type];
    }

    constexpr long DAY_SECONDS = 24 * 60 * 60;

    void
    ConvertTimeRangeToDBDates(const std::vector<::milvus::grpc::Range> &range_array,
                              std::vector<DB_DATE> &dates,
                              ServerError &error_code,
                              std::string &error_msg) {
        dates.clear();
        for (auto &range : range_array) {
            time_t tt_start, tt_end;
            tm tm_start, tm_end;
            if (!CommonUtil::TimeStrToTime(range.start_value(), tt_start, tm_start)) {
                error_code = SERVER_INVALID_TIME_RANGE;
                error_msg = "Invalid time range: " + range.start_value();
                return;
            }

            if (!CommonUtil::TimeStrToTime(range.end_value(), tt_end, tm_end)) {
                error_code = SERVER_INVALID_TIME_RANGE;
                error_msg = "Invalid time range: " + range.start_value();
                return;
            }

            long days = (tt_end > tt_start) ? (tt_end - tt_start) / DAY_SECONDS : (tt_start - tt_end) /
                                                                                  DAY_SECONDS;
            if (days == 0) {
                error_code = SERVER_INVALID_TIME_RANGE;
                error_msg = "Invalid time range: " + range.start_value() + " to " + range.end_value();
                return;
            }

            for (long i = 0; i < days; i++) {
                time_t tt_day = tt_start + DAY_SECONDS * i;
                tm tm_day;
                CommonUtil::ConvertTime(tt_day, tm_day);

                long date = tm_day.tm_year * 10000 + tm_day.tm_mon * 100 +
                            tm_day.tm_mday;//according to db logic
                dates.push_back(date);
            }
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CreateTableTask::CreateTableTask(const ::milvus::grpc::TableSchema &schema)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          schema_(schema) {

}

BaseTaskPtr
CreateTableTask::Create(const ::milvus::grpc::TableSchema &schema) {
    return std::shared_ptr<GrpcBaseTask>(new CreateTableTask(schema));
}

ServerError
CreateTableTask::OnExecute() {
    TimeRecorder rc("CreateTableTask");

    try {
        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(schema_.table_name().table_name());
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + schema_.table_name().table_name());
        }

        res = ValidationUtil::ValidateTableDimension(schema_.dimension());
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table dimension: " + std::to_string(schema_.dimension()));
        }

        res = ValidationUtil::ValidateTableIndexType(schema_.index_type());
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid index type: " + std::to_string(schema_.index_type()));
        }

        //step 2: construct table schema
        engine::meta::TableSchema table_info;
        table_info.dimension_ = (uint16_t) schema_.dimension();
        table_info.table_id_ = schema_.table_name().table_name();
        table_info.engine_type_ = (int) EngineType(schema_.index_type());
        table_info.store_raw_data_ = schema_.store_raw_vector();

        //step 3: create table
        engine::Status stat = DBWrapper::DB()->CreateTable(table_info);
        if (!stat.ok()) {
            //table could exist
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    rc.ElapseFromBegin("totally cost");

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
DescribeTableTask::DescribeTableTask(const std::string &table_name, ::milvus::grpc::TableSchema &schema)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          table_name_(table_name),
          schema_(schema) {
}

BaseTaskPtr
DescribeTableTask::Create(const std::string &table_name, ::milvus::grpc::TableSchema &schema) {
    return std::shared_ptr<GrpcBaseTask>(new DescribeTableTask(table_name, schema));
}

ServerError
DescribeTableTask::OnExecute() {
    TimeRecorder rc("DescribeTableTask");

    try {
        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        //step 2: get table info
        engine::meta::TableSchema table_info;
        table_info.table_id_ = table_name_;
        engine::Status stat = DBWrapper::DB()->DescribeTable(table_info);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        schema_.mutable_table_name()->set_table_name(table_info.table_id_);

        schema_.set_index_type(IndexType((engine::EngineType) table_info.engine_type_));
        schema_.set_dimension(table_info.dimension_);
        schema_.set_store_raw_vector(table_info.store_raw_data_);

    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    rc.ElapseFromBegin("totally cost");

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CreateIndexTask::CreateIndexTask(const ::milvus::grpc::IndexParam &index_param)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          index_param_(index_param) {
}

BaseTaskPtr
CreateIndexTask::Create(const ::milvus::grpc::IndexParam &index_param) {
    return std::shared_ptr<GrpcBaseTask>(new CreateIndexTask(index_param));
}

ServerError
CreateIndexTask::OnExecute() {
    try {
        TimeRecorder rc("CreateIndexTask");

        //step 1: check arguments
        std::string table_name_ = index_param_.table_name().table_name();
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        bool has_table = false;
        engine::Status stat = DBWrapper::DB()->HasTable(table_name_, has_table);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        if (!has_table) {
            return SetError(SERVER_TABLE_NOT_EXIST, "Table " + table_name_ + " not exists");
        }

        //step 2: check table existence
        stat = DBWrapper::DB()->BuildIndex(table_name_);
        if (!stat.ok()) {
            return SetError(SERVER_BUILD_INDEX_ERROR, "Engine failed: " + stat.ToString());
        }

        rc.ElapseFromBegin("totally cost");
    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
HasTableTask::HasTableTask(const std::string &table_name, bool &has_table)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          table_name_(table_name),
          has_table_(has_table) {

}

BaseTaskPtr
HasTableTask::Create(const std::string &table_name, bool &has_table) {
    return std::shared_ptr<GrpcBaseTask>(new HasTableTask(table_name, has_table));
}

ServerError
HasTableTask::OnExecute() {
    try {
        TimeRecorder rc("HasTableTask");

        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        //step 2: check table existence
        engine::Status stat = DBWrapper::DB()->HasTable(table_name_, has_table_);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        rc.ElapseFromBegin("totally cost");
    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
DropTableTask::DropTableTask(const std::string &table_name)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          table_name_(table_name) {

}

BaseTaskPtr
DropTableTask::Create(const std::string &table_name) {
    return std::shared_ptr<GrpcBaseTask>(new DropTableTask(table_name));
}

ServerError
DropTableTask::OnExecute() {
    try {
        TimeRecorder rc("DropTableTask");

        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        //step 2: check table existence
        engine::meta::TableSchema table_info;
        table_info.table_id_ = table_name_;
        engine::Status stat = DBWrapper::DB()->DescribeTable(table_info);
        if (!stat.ok()) {
            if (stat.IsNotFound()) {
                return SetError(SERVER_TABLE_NOT_EXIST, "Table " + table_name_ + " not exists");
            } else {
                return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
            }
        }

        rc.ElapseFromBegin("check validation");

        //step 3: Drop table
        std::vector<DB_DATE> dates;
        stat = DBWrapper::DB()->DeleteTable(table_name_, dates);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        rc.ElapseFromBegin("total cost");
    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
ShowTablesTask::ShowTablesTask(::grpc::ServerWriter<::milvus::grpc::TableName> &writer)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          writer_(writer) {

}

BaseTaskPtr
ShowTablesTask::Create(::grpc::ServerWriter<::milvus::grpc::TableName> &writer) {
    return std::shared_ptr<GrpcBaseTask>(new ShowTablesTask(writer));
}

ServerError
ShowTablesTask::OnExecute() {
    std::vector<engine::meta::TableSchema> schema_array;
    engine::Status stat = DBWrapper::DB()->AllTables(schema_array);
    if (!stat.ok()) {
        return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
    }

    for (auto &schema : schema_array) {
        ::milvus::grpc::TableName tableName;
        tableName.set_table_name(schema.table_id_);
        if (!writer_.Write(tableName)) {
            return SetError(SERVER_WRITE_ERROR, "Write table name failed!");
        }
    }
    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
InsertTask::InsertTask(const ::milvus::grpc::InsertParam &insert_param,
                                   ::milvus::grpc::VectorIds &record_ids)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          insert_param_(insert_param),
          record_ids_(record_ids) {
    record_ids_.Clear();
}

BaseTaskPtr
InsertTask::Create(const ::milvus::grpc::InsertParam &insert_param,
                         ::milvus::grpc::VectorIds &record_ids) {
    return std::shared_ptr<GrpcBaseTask>(new InsertTask(insert_param, record_ids));
}

ServerError
InsertTask::OnExecute() {
    try {
        TimeRecorder rc("InsertVectorTask");

        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(insert_param_.table_name());
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + insert_param_.table_name());
        }
        if (insert_param_.row_record_array().empty()) {
            return SetError(SERVER_INVALID_ROWRECORD_ARRAY, "Row record array is empty");
        }

        if (!record_ids_.vector_id_array().empty()) {
            if (record_ids_.vector_id_array().size() != insert_param_.row_record_array_size()) {
                return SetError(SERVER_ILLEGAL_VECTOR_ID,
                        "Size of vector ids is not equal to row record array size");
            }
        }

        //step 2: check table existence
        engine::meta::TableSchema table_info;
        table_info.table_id_ = insert_param_.table_name();
        engine::Status stat = DBWrapper::DB()->DescribeTable(table_info);
        if (!stat.ok()) {
            if (stat.IsNotFound()) {
                return SetError(SERVER_TABLE_NOT_EXIST,
                                "Table " + insert_param_.table_name() + " not exists");
            } else {
                return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
            }
        }

        rc.RecordSection("check validation");

#ifdef MILVUS_ENABLE_PROFILING
        std::string fname = "/tmp/insert_" + std::to_string(this->record_array_.size()) +
                            "_" + GetCurrTimeStr() + ".profiling";
        ProfilerStart(fname.c_str());
#endif

        //step 3: prepare float data
        std::vector<float> vec_f(insert_param_.row_record_array_size() * table_info.dimension_, 0);

        // TODO: change to one dimension array in protobuf or use multiple-thread to copy the data
        for (size_t i = 0; i < insert_param_.row_record_array_size(); i++) {
            for (size_t j = 0; j < table_info.dimension_; j++) {
                if (insert_param_.row_record_array(i).vector_data().empty()) {
                    return SetError(SERVER_INVALID_ROWRECORD_ARRAY, "Row record float array is empty");
                }
                uint64_t vec_dim = insert_param_.row_record_array(i).vector_data().size();
                if (vec_dim != table_info.dimension_) {
                    ServerError error_code = SERVER_INVALID_VECTOR_DIMENSION;
                    std::string error_msg = "Invalid rowrecord dimension: " + std::to_string(vec_dim)
                                            + " vs. table dimension:" +
                                            std::to_string(table_info.dimension_);
                    return SetError(error_code, error_msg);
                }
                vec_f[i * table_info.dimension_ + j] = insert_param_.row_record_array(i).vector_data(j);
            }
        }

        rc.ElapseFromBegin("prepare vectors data");

        //step 4: insert vectors
        auto vec_count = (uint64_t) insert_param_.row_record_array_size();
        std::vector<int64_t> vec_ids(record_ids_.vector_id_array_size(), 0);

        stat = DBWrapper::DB()->InsertVectors(insert_param_.table_name(), vec_count, vec_f.data(),
                                              vec_ids);
        rc.ElapseFromBegin("add vectors to engine");
        if (!stat.ok()) {
            return SetError(SERVER_CACHE_ERROR, "Cache error: " + stat.ToString());
        }
        for (int64_t id : vec_ids) {
            record_ids_.add_vector_id_array(id);
        }

        auto ids_size = record_ids_.vector_id_array_size();
        if (ids_size != vec_count) {
            std::string msg = "Add " + std::to_string(vec_count) + " vectors but only return "
                              + std::to_string(ids_size) + " id";
            return SetError(SERVER_ILLEGAL_VECTOR_ID, msg);
        }

#ifdef MILVUS_ENABLE_PROFILING
        ProfilerStop();
#endif

        rc.RecordSection("add vectors to engine");
        rc.ElapseFromBegin("total cost");

    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SearchTask::SearchTask(const ::milvus::grpc::SearchParam &search_vector_infos,
                                   const std::vector<std::string> &file_id_array,
                                   ::grpc::ServerWriter<::milvus::grpc::TopKQueryResult> &writer)
        : GrpcBaseTask(DQL_TASK_GROUP),
          search_param_(search_vector_infos),
          file_id_array_(file_id_array),
          writer_(writer) {

}

BaseTaskPtr
SearchTask::Create(const ::milvus::grpc::SearchParam &search_vector_infos,
                         const std::vector<std::string> &file_id_array,
                         ::grpc::ServerWriter<::milvus::grpc::TopKQueryResult> &writer) {
    return std::shared_ptr<GrpcBaseTask>(new SearchTask(search_vector_infos, file_id_array,
                                                              writer));
}

ServerError
SearchTask::OnExecute() {
    try {
        TimeRecorder rc("SearchTask");

        //step 1: check arguments
        std::string table_name_ = search_param_.table_name();
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        int64_t top_k_ = search_param_.topk();

        if (top_k_ <= 0 || top_k_ > 1024) {
            return SetError(SERVER_INVALID_TOPK, "Invalid topk: " + std::to_string(top_k_));
        }

        int64_t nprobe = search_param_.nprobe();
        if (nprobe <= 0) {
            return SetError(SERVER_INVALID_NPROBE, "Invalid nprobe: " + std::to_string(nprobe));
        }

        if (search_param_.query_record_array().empty()) {
            return SetError(SERVER_INVALID_ROWRECORD_ARRAY, "Row record array is empty");
        }

        //step 2: check table existence
        engine::meta::TableSchema table_info;
        table_info.table_id_ = table_name_;
        engine::Status stat = DBWrapper::DB()->DescribeTable(table_info);
        if (!stat.ok()) {
            if (stat.IsNotFound()) {
                return SetError(SERVER_TABLE_NOT_EXIST, "Table " + table_name_ + " not exists");
            } else {
                return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
            }
        }

        //step 3: check date range, and convert to db dates
        std::vector<DB_DATE> dates;
        ServerError error_code = SERVER_SUCCESS;
        std::string error_msg;

        std::vector<::milvus::grpc::Range> range_array;
        for (size_t i = 0; i < search_param_.query_range_array_size(); i++) {
            range_array.emplace_back(search_param_.query_range_array(i));
        }
        ConvertTimeRangeToDBDates(range_array, dates, error_code, error_msg);
        if (error_code != SERVER_SUCCESS) {
            return SetError(error_code, error_msg);
        }

        double span_check = rc.RecordSection("check validation");

#ifdef MILVUS_ENABLE_PROFILING
        std::string fname = "/tmp/search_nq_" + std::to_string(this->record_array_.size()) +
                            "_top_" + std::to_string(this->top_k_) + "_" +
                            GetCurrTimeStr() + ".profiling";
        ProfilerStart(fname.c_str());
#endif

        //step 3: prepare float data
        auto record_array_size = search_param_.query_record_array_size();
        std::vector<float> vec_f(record_array_size * table_info.dimension_, 0);
        for (size_t i = 0; i < record_array_size; i++) {
            for (size_t j = 0; j < table_info.dimension_; j++) {
                if (search_param_.query_record_array(i).vector_data().empty()) {
                    return SetError(SERVER_INVALID_ROWRECORD_ARRAY,
                                    "Query record float array is empty");
                }
                uint64_t query_vec_dim = search_param_.query_record_array(
                        i).vector_data().size();
                if (query_vec_dim != table_info.dimension_) {
                    ServerError error_code = SERVER_INVALID_VECTOR_DIMENSION;
                    std::string error_msg =
                            "Invalid rowrecord dimension: " + std::to_string(query_vec_dim)
                            + " vs. table dimension:" + std::to_string(table_info.dimension_);
                    return SetError(error_code, error_msg);
                }
                vec_f[i * table_info.dimension_ + j] = search_param_.query_record_array(
                        i).vector_data(j);
            }
        }
        rc.ElapseFromBegin("prepare vector data");

        //step 4: search vectors
        engine::QueryResults results;
        auto record_count = (uint64_t) search_param_.query_record_array().size();

        if (file_id_array_.empty()) {
            stat = DBWrapper::DB()->Query(table_name_, (size_t) top_k_, record_count, nprobe, vec_f.data(),
                                          dates, results);
        } else {
            stat = DBWrapper::DB()->Query(table_name_, file_id_array_, (size_t) top_k_,
                                          record_count, nprobe, vec_f.data(), dates, results);
        }

        rc.ElapseFromBegin("search vectors from engine");
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        if (results.empty()) {
            return SERVER_SUCCESS; //empty table
        }

        if (results.size() != record_count) {
            std::string msg = "Search " + std::to_string(record_count) + " vectors but only return "
                              + std::to_string(results.size()) + " results";
            return SetError(SERVER_ILLEGAL_SEARCH_RESULT, msg);
        }

        rc.ElapseFromBegin("do search");

        //step 5: construct result array
        for (uint64_t i = 0; i < record_count; i++) {
            auto &result = results[i];
            const auto &record = search_param_.query_record_array(i);
            ::milvus::grpc::TopKQueryResult grpc_topk_result;
            for (auto &pair : result) {
                ::milvus::grpc::QueryResult *grpc_result = grpc_topk_result.add_query_result_arrays();
                grpc_result->set_id(pair.first);
                grpc_result->set_distance(pair.second);
            }
            if (!writer_.Write(grpc_topk_result)) {
                return SetError(SERVER_WRITE_ERROR, "Write topk result failed!");
            }
        }

#ifdef MILVUS_ENABLE_PROFILING
        ProfilerStop();
#endif

        double span_result = rc.RecordSection("construct result");
        rc.ElapseFromBegin("totally cost");

        //step 6: print time cost percent

    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CountTableTask::CountTableTask(const std::string &table_name, int64_t &row_count)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          table_name_(table_name),
          row_count_(row_count) {

}

BaseTaskPtr
CountTableTask::Create(const std::string &table_name, int64_t &row_count) {
    return std::shared_ptr<GrpcBaseTask>(new CountTableTask(table_name, row_count));
}

ServerError
CountTableTask::OnExecute() {
    try {
        TimeRecorder rc("GetTableRowCountTask");

        //step 1: check arguments
        ServerError res = SERVER_SUCCESS;
        res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        //step 2: get row count
        uint64_t row_count = 0;
        engine::Status stat = DBWrapper::DB()->GetTableRowCount(table_name_, row_count);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        row_count_ = (int64_t) row_count;

        rc.ElapseFromBegin("total cost");

    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
CmdTask::CmdTask(const std::string &cmd, std::string &result)
        : GrpcBaseTask(PING_TASK_GROUP),
          cmd_(cmd),
          result_(result) {

}

BaseTaskPtr
CmdTask::Create(const std::string &cmd, std::string &result) {
    return std::shared_ptr<GrpcBaseTask>(new CmdTask(cmd, result));
}

ServerError
CmdTask::OnExecute() {
    if (cmd_ == "version") {
        result_ = MILVUS_VERSION;
    } else {
        result_ = "OK";
    }

    return SERVER_SUCCESS;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
PreloadTableTask::PreloadTableTask(const std::string &table_name)
        : GrpcBaseTask(DDL_DML_TASK_GROUP),
          table_name_(table_name) {

}

BaseTaskPtr
PreloadTableTask::Create(const std::string &table_name){
    return std::shared_ptr<GrpcBaseTask>(new PreloadTableTask(table_name));
}

ServerError
PreloadTableTask::OnExecute() {
    try {
        TimeRecorder rc("PreloadTableTask");

        //step 1: check arguments
        ServerError res = ValidationUtil::ValidateTableName(table_name_);
        if (res != SERVER_SUCCESS) {
            return SetError(res, "Invalid table name: " + table_name_);
        }

        //step 2: check table existence
        engine::Status stat = DBWrapper::DB()->PreloadTable(table_name_);
        if (!stat.ok()) {
            return SetError(DB_META_TRANSACTION_FAILED, "Engine failed: " + stat.ToString());
        }

        rc.ElapseFromBegin("totally cost");
    } catch (std::exception &ex) {
        return SetError(SERVER_UNEXPECTED_ERROR, ex.what());
    }

    return SERVER_SUCCESS;
}



}
}
}
}