This is a question related to C# MVC2 Jqgrid - what is the correct way to do server side paging? where I asked and found how to improve the performance for a query on a table with 2000 or so rows. The performance was improved from 10 seconds to 1 second.
Now I'm trying to perform the exact same query where the table has 20,000 rows - and the query takes 30 seconds. How can I improve it further? 20 thousand rows is still not a huge number at all.
Some possible ideas I have are:
- It can be improved by de-normalizing to remove joins and sums
- Make a view and query that instead of querying and joining the table
- Don't query the whole table, make the user select some filter first (eg an A | B | C .. etc filter)
- Add more indexes to the tables
- Something else?
This is the MVC action that takes 30 seconds for 20 thousand rows: (the parameters are supplied by jqgrid, where sidx = which sort column, and sord = the sort order)
public ActionResult GetProductList(int page, int rows, string sidx, string sord,
string searchOper, string searchField, string searchString)
{
if (sidx == "Id") { sidx = "ProductCode"; }
var pagedData = _productService.GetPaged(sidx, sord, page, rows);
var model = (from p in pagedData.Page<Product>()
select new
{
p.Id, p.ProductCode, p.ProductDescription,
Barcode = p.Barcode ?? string.Empty,
UnitOfMeasure = p.UnitOfMeasure != null ? p.UnitOfMeasure.Name : "",
p.PackSize,
AllocatedQty = p.WarehouseProducts.Sum(wp => wp.AllocatedQuantity),
QtyOnHand = p.WarehouseProducts.Sum(wp => wp.OnHandQuantity)
});
var jsonData = new
{
Total = pagedData.TotalPages, Page = pagedData.PageNumber,
Records = pagedData.RecordCount, Rows = model
};
return Json(jsonData, JsonRequestBehavior.AllowGet);
}
ProductService.GetPaged() calls ProductRepository.GetPaged which calls genericRepository.GetPaged() which does this:
public ListPage GetPaged(string sidx, string sord, int page, int rows)
{
var list = GetQuery().OrderBy(sidx + " " + sord);
int totalRecords = list.Count();
var listPage = new ListPage
{
TotalPages = (totalRecords + rows - 1) / rows,
PageNumber = page,
RecordCount = totalRecords,
};
listPage.SetPageData(list
.Skip((page > 0 ? page - 1 : 0) * rows)
.Take(rows).AsQueryable());
return listPage;
}
The .OrderBy() clause uses LinqExtensions so that I can pass in a string instead of a predicate - could this be slowing it down?
And finally ListPage is just a class for conveniently wrapping up the properties that jqgrid needs for paging:
public class ListPage
{
private IQueryable _data;
public int TotalPages { get; set; }
public int PageNumber { get; set; }
public int RecordCount { get; set; }
public void SetPageData<T>(IQueryable<T> data)
{
_data = data;
}
public IQueryable<T> Page<T>()
{
return (IQueryable<T>)_data;
}
}
GetQuery is:
public IQueryable<T> GetQuery()
{
return ObjectSet.AsQueryable();
}
The custom .OrderBy method consists of these two methods:
public static IQueryable<T> OrderBy<T>(this IQueryable<T> source,
string ordering, params object[] values)
{
return (IQueryable<T>)OrderBy((IQueryable)source, ordering, values);
}
public static IQueryable OrderBy(this IQueryable source, string ordering,
params object[] values)
{
if (source == null) throw new ArgumentNullException("source");
if (ordering == null) throw new ArgumentNullException("ordering");
ParameterExpression[] parameters = new ParameterExpression[] {
Expression.Parameter(source.ElementType, "") };
ExpressionParser parser = new ExpressionParser(parameters, ordering, values);
IEnumerable<DynamicOrdering> orderings = parser.ParseOrdering();
Expression queryExpr = source.Expression;
string methodAsc = "OrderBy";
string methodDesc = "OrderByDescending";
foreach (DynamicOrdering o in orderings)
{
queryExpr = Expression.Call(
typeof(Queryable), o.Ascending ? methodAsc : methodDesc,
new Type[] { source.ElementType, o.Selector.Type },
queryExpr, Expression.Quote(Expression.Lambda(o.Selector, parameters)));
methodAsc = "ThenBy";
methodDesc = "ThenByDescending";
}
return source.Provider.CreateQuery(queryExpr);
}
