SubscribeBar函数

OnInit()
    {
    
        //设置最大回溯bar数，用于序列变量预分配内存，不能比序列变量实际最大回溯bar数小
        SubscribeBar("000300.SSE", "15M",20070416);
        /*SubscribeBar("000300.SSE","30M",20100701);
        SubscribeBar("000300.SSE","1H",20100701);
        SubscribeBar("000300.SSE","2H",20100701);
        SubscribeBar("000300.SSE","1D",201007011);
        SubscribeBar("IF888.CFFEX","15M",20100416);*/
    }

策略研究中bar数怎么只有5000，请大神们指教