query cloud db raw data need longtime : 100 gps track's raw data(about 11Mb) need 16sencods
why so slow?
guess 1 : data size is too large , slow is caused by network transport.
guess 2 : query is not good, db find the track need a longtime.
use the explain analyze to show the time of query
plantime : sql choose which method to excute the query

guess 1 failed. download time is 7.61ms.
so guess 2 is good , but how to optimize query.

that my query:

function searchByRaceRecordId(raceRecordId) {
    var sql = 'select racerecordid,utc,fix,latitude,longitude,cloudracetext.realdistance,gpsheight,gpsspeed,direction from cloudracetext where racerecordid = $1';
    var params = [raceRecordId];

    return new Promise(function (resolve, reject) {
        pg_client.query(sql, params, (err,res) => {
            if(err)
            {
                reject(err);
            }
            else
            {
                resolve(model_make_race_track_rawdata(res['rows']));
                // resolve(res['rows']);
            }
        });
    });

};

function searchByRaceRecordIdList(raceRecordId_list) {
    console.log('start prepare raw data');
    var starttime = Date.now();
    var functionList = [];
    for(var i=0;i<raceRecordId_list.length;i++)
    {
        functionList.push(searchByRaceRecordId(raceRecordId_list[i]));
    }

    return new Promise(function(resolve,reject){
        Promise.all(functionList)
        .then(values=>{
            var endtime = Date.now();
            console.log('data prepared',endtime.toString() - starttime.toString());
            resolve(values);
        })
        .catch(errs=>{
            reject(errs);
        });
    })
};

optimize method : use the IN (list) to send a single query to cloudb.

function searchByRaceRecordIdList_optimize(raceRecordId_list) {
    console.log('start prepare raw data');
    var starttime = Date.now();
    console.log(raceRecordId_list.length);
    var params = [];
    for(var i = 1; i <= raceRecordId_list.length; i++) {
        params.push('$' + i);
    }
    console.log(params);

    var sql = 'select racerecordid,utc,fix,latitude,longitude,cloudracetext.realdistance,gpsheight,gpsspeed,direction from cloudracetext where racerecordid IN (' + params.join(',') + ')';
    console.log(sql);
    return new Promise(function (resolve, reject) {
        pg_client.query(sql, raceRecordId_list, (err,res) => {
            if(err)
            {
                reject(err);
            }
            else
            {
                var endtime = Date.now();
                console.log('data prepared',endtime.toString() - starttime.toString());
                // resolve(model_make_race_track_rawdata(res['rows']));
                resolve(model_make_race_track_rawdata(res['rows']));
            }
        });
    });
};

that's the result