Question

我读过很多关于LINQ和Where子句的文章。我几乎没有尝试创建良好的PagedList机制。此时从数据库中获取100个对象需要大约3秒进行查询，但是当我添加Where子句时，它会慢慢减慢到大约10-13秒。

我的代码：

public IPagedList<WsPolice> GetPoliciesListLINQ(NavigationModule navModule, List<int> userChildren)
{
    // IQueryable object
    var query = _session.Query<WsPolice>();

    // right filters
    query = GetPolicyCriteriaLINQ(query, navModule, userChildren);

    // search query
    query = AddSearchToQuery(query, navModule);            

    // order
    query = query.CustomOrder(navModule.CurrentSortAtrribute ?? navModule.DefaultSortAttribute, navModule.isAsceding.HasValue && navModule.isAsceding.Value);

    // pagedlist
    var finalList = query.ToPagedList(navModule.Page.Value, navModule.ItemsOnPage.Value);

    return finalList;
}

AddSearchToQuery函数会产生问题：

public IQueryable<WsPolice> AddSearchToQuery(IQueryable<WsPolice> query, NavigationModule navModule)
{
    // add query if string is not null
    if (!string.IsNullOrEmpty(navModule.CurrentSearchString))
    {
        query = query.Where(GetPolicySearchExpression(navModule.CurrentSearchString));
    }
}

public Expression<Func<WsPolice, bool>> GetPolicySearchExpression(string query)
{
    query = query.ToLower();

    return
        x =>
                    x.policyDateEnd.ToString().ToLower().Contains(query) ||
                    x.policyDate.ToString().ToLower().Contains(query) ||
                    x.policyNr.ToLower().Contains(query) ||
                    x.policyAmount.ToString().ToLower().Contains(query) ||
                    x.policyDue.ToString().ToLower().Contains(query) ||
                    x.policyCollectionAmount.ToString().ToLower().Contains(query) ||
                    x.wsUsers.userName.ToLower().Contains(query) ||
                    x.wsUsers.userSname.ToLower().Contains(query) ||
                    x.wsUsers.userCompanyName.ToLower().Contains(query) ||
                    x.wsUsersIssuing.userName.ToLower().Contains(query) ||
                    x.wsUsersIssuing.userSname.ToLower().Contains(query) ||
                    x.wsUsersIssuing.userCompanyName.ToLower().Contains(query) ||
                    x.wsUsersIssuing.userAgentId.ToLower().Contains(query) ||
                    x.wsVehicles.vehicleRegNumber.ToLower().Contains(query) ||
                    x.wsVehicles.vehicleBrand.ToLower().Contains(query) ||
                    x.wsVehicles.vehicleModel.ToLower().Contains(query) ||
                    x.wsUsers.userPesel.ToLower().Contains(query) ||
                    x.wsUsers.userRegon.ToLower().Contains(query) ||
                    x.wsVehicles.VehicleCoowners.Select(y => (y.CoownerPesel ?? "").ToLower()).Any(z => z.Contains(query)) ||
                    x.wsVehicles.VehicleCoowners.Select(y => (y.CoownerName ?? "").ToLower()).Any(z => z.Contains(query)) ||
                    x.wsVehicles.VehicleCoowners.Select(y => (y.CoownerSname ?? "").ToLower()).Any(z => z.Contains(query)) ||
                    x.WsPolicyAliases.Select(y => (y.AliasName ?? "").ToLower()).Any(z => z.Contains(query));

}

正如许多文章建议的那样，我使用Expression<Func<T, bool>>因为它比Func<T, bool>更快。我的对象总是IQueryable，而不是IEnumerable。我究竟做错了什么？我试图用一对多的关系来评论这些行，但它并没有改变性能。

我使用了NhibernateProfiler并得到了这个：link，最后一个AND语句需要7秒。

LINQ - 即使使用Expression <func <t，bool =“”>＆gt;

0 个答案: