We found out during SQL profiling that when bound to an IQueryable (linked to DbContext) with pagination enabled, the Telerik data grid called SQL to count elements twice. This is not a pre-render problem as those deplicated queries are actually executed twice (one pair for each render).

Our simplified code:

<TelerikGrid TItem="Item"
             Data="_data"
             PageSize="10"
             Pageable="true"
             Sortable="true">
    <GridColumns>
        <GridColumn Field="@nameof(Item.Id)" />
        <GridColumn Field="@nameof(Item.Code)" />
    </GridColumns>
</TelerikGrid>

@code {
    [Inject] protected DbContext DbContext { get; set; }

    private IEnumerable<Item> _data;

    protected override void OnInitialized()
    {
        base.OnInitialized();
        _data = DbContext.Items
            .Select(x => new Item()
            {
                Id = x.Id,
                Code = x.Code
            });
    }
}

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ADMIN EDIT:

There are two possible ways to avoid the double COUNT:

• Enumerate the collection before binding the Grid. For example, call ToList().
• Bind the Grid via OnRead event. This gives full control over the data binding process and possible optimizations.