Enhance Performance on Large Datasets

If the DataGrid is going to work with a large dataset, we recommend delegating data processing operations to the server as described in the Custom Sources topic. Additionally, you can make the following tweaks to enhance the DataGrid's performance.

Deferred Selection

Use the deferred mode to increase the DataGrid's performance when selecting multiple rows at once. In this mode, only the API - for example, the getSelectedRowsData() or getSelectedRowKeys() method - can request the DataGrid data. Assign true to the selection.deferred option to use deferred selection.

jQuery
JavaScript
$(function(){
    $("#dataGridContainer").dxDataGrid({
        // ...
        dataSource: {
            store: {
                type: "odata",
                url: "https://js.devexpress.com/Demos/DevAV/odata/Products",
                key: "Product_ID"
            }
        },
        selection: {
            mode: 'multiple',
            allowSelectAll: true,
            deferred: true
        }
    }); 
});
Angular
HTML
TypeScript
<dx-data-grid
    [dataSource]="dataSource">
    <dxo-selection
        mode="multiple"
        [allowSelectAll]="true"
        [deferred]="true">
    </dxo-selection>
</dx-data-grid>
import { DxDataGridModule } from 'devextreme-angular';
import 'devextreme/data/odata/store';
// ...
export class AppComponent {
    dataSource = {
        store: {
            type: "odata",
            url: "https://js.devexpress.com/Demos/DevAV/odata/Products",
            key: "Product_ID"
        }
    }
}
@NgModule({
    imports: [
        // ...
        DxDataGridModule
    ],
    // ...
})
NOTE
You must specify the key option of the Store underlying the dataSource to guarantee that the deferred selection works properly.

The following tasks require using different API in the deferred mode comparing with usual (instant) one:

  • Setting initial selection

    The deferred mode requires using the selectionFilter instead of the selectedRowKeys option to set the initially selected rows. Pass a filter expression to define records that must be selected.

    jQuery
    JavaScript
    $(function () {
        $("#dataGridContainer").dxDataGrid({
            // ...
            selectionFilter: ["Task_Status", "=", "Completed"]
        });
    });
    Angular
    HTML
    TypeScript
    <dx-data-grid ...
        selectionFilter="['Task_Status', '=', 'Completed']">
    </dx-data-grid>
    import { DxDataGridModule } from 'devextreme-angular';
    // ...
    export class AppComponent {
        // ...
    }
    @NgModule({
        imports: [
            // ...
            DxDataGridModule
        ],
        // ...
    })

    The DataGrid changes the selectionFilter option's value internally each time a user selects a row. You can use the following code to obtain this option's current value and send it to the server:

    jQuery
    JavaScript
    function sendSelectedRows() {
        var selectionFilter = dataGridInstance.option("selectionFilter");
        $.ajax({
            method: "POST",
            url: "url/to/data/processing/method",
            data: { 
                filter: (selectionFilter ? JSON.stringify(selectionFilter) : null)
            }
        });
    }
    Angular
    TypeScript
    import { ..., ViewChild } from '@angular/core';
    import { Http, HttpModule } from '@angular/http';
    import { DxDataGridModule, DxDataGridComponent } from 'devextreme-angular';
    // ...
    export class AppComponent {
        @ViewChild(DxDataGridComponent) dataGrid: DxDataGridComponent;
        constructor(private http: Http) { }
        sendSelectedRows() {
            var selectionFilter = this.dataGrid.instance.option("selectionFilter");
            this.http
                .post('url/to/data/processing/method',  
                "filter: " + (selectionFilter ? JSON.stringify(selectionFilter) : null)
                )
                .subscribe();
        }
    }
    @NgModule({
        imports: [
            // ...
            DxDataGridModule,
            HttpModule
        ],
        // ...
    })
  • Checking whether a row is selected

    Use the isRowSelected(data) method to find out whether a specific row is selected.

  • Getting the selected rows' data

    In the deferred mode, the getSelectedRowsData() and getSelectedRowKeys() methods return a jQuery.Deferred object's Promise. Get the selected data within the callback function that resolves this object.

View Demo

See Also

Lookup Optimization

As a rule, a lookup column contains IDs from a main data source field but displays human-readable values from its own data source. When the DataGrid first launches, it loads data from both data sources which causes performance to decrease.

You can send the human-readable values from the server as a part of the main data source alongside the IDs (like in this example) to optimize the lookup column. In this case, use the column's calculateDisplayValue option to specify which field provides the human-readable values. With this optimization, the lookup data source is not loaded until a user starts editing the lookup column.

jQuery
JavaScript
$(function () {
    $("#dataGridContainer").dxDataGrid({
        //...
        columns: [{
            caption: "Customer",
            // "CustomerName" provides human-readable values
            calculateDisplayValue: "CustomerName",
            dataField: "CustomerID",
            lookup: {
                valueExpr: "CustomerID",
                displayExpr: "ContactName",
                dataSource: {
                    store: {
                        // ...
                        key: "CustomerID"
                    }
                }
            }
        },
        // ...
        ]
    });
});
Angular
HTML
TypeScript
<dx-data-grid ...>
    <dxi-column
        caption="Customer"
        dataField="CustomerID"
        calculateDisplayValue="CustomerName">   <!-- "CustomerName" provides human-readable values -->
        <dxo-lookup
            [dataSource]="dataSource"
            displayExpr="ContactName"
            valueExpr="CustomerID">
        </dxo-lookup>
    </dxi-column>
</dx-data-grid>
import { DxDataGridModule } from 'devextreme-angular';
import 'devextreme/data/array_store';
// or
// import 'devextreme/data/odata/store';
// import 'devextreme/data/custom_store';
export class AppComponent {
    dataSource: any;
    constructor() {
        this.dataSource = {
            store: {
                // ...
                key: "CustomerID"
            }
        }
    }
}
@NgModule({
    imports: [
        // ...
        DxDataGridModule
    ],
    // ...
})
See Also

Remote Group Paging

Remote group paging is a feature that allows loading groups from a remote source in portions. With it, the DataGrid transmits significantly less data, thus speeding up grouping. As a downside, requests become more frequent, because the DataGrid sends several of them each time a user expands a group or sorts/filters data.

When using remote group paging, the following restrictions apply:

  • The server should perform filtering, paging, grouping, and sorting;
  • All groups should be collapsed initially by setting the grouping.autoExpandAll option to false;
  • The expandAll(groupIndex) method should not be called. Otherwise, the widget ignores remote group paging.

Set the remoteOperations.groupPaging option to true to enable remote group paging. Note that with this setting, all other data processing operations (filtering, sorting, grouping, paging and summary calculation) also become remote.

jQuery
JavaScript
$(function() {
    $("#dataGridContainer").dxDataGrid({
        //...
        remoteOperations: {
            groupPaging: true
        }
    });
});
Angular
HTML
TypeScript
<dx-data-grid ... >
    <dxo-remote-operations [groupPaging]="true"></dxo-remote-operations>
</dx-data-grid>
import { DxDataGridModule } from 'devextreme-angular';
// ...
export class AppComponent {
    // ...
}
@NgModule({
    imports: [
        // ...
        DxDataGridModule
    ],
    // ...
})

Now, the DataGrid requires server-implemented group paging. Use the following ASP.NET and PHP server extensions to implement group paging and other data processing operations:

For servers built on other technologies, implement all data processing operations by yourself and configure data access on the client side using the CustomStore as shown in the Custom Sources - Load Data topic. Mind that the result object described in there should also contain the groupCount field specifying the count of top-level groups, and the items field of each data object should be equal to null.

{
    data: [{
        key: "Group 1",
        count: 3,
        items: null,
        summary: [30, 20, 40]
    },
    ...
    ], 
    totalCount: 200,
    groupCount: 35, // this field added; count of top-level groups returned if requireGroupCount is true
    summary: [170, 20, 20, 1020]
}

The groupCount should be returned only if the requireGroupCount parameter in the loadOptions is true. The following code is amended to query data from a server that supports remote group paging:

jQuery
JavaScript
var gridDataSource = new DevExpress.data.DataSource({
    load: function (loadOptions) {
        var d = $.Deferred();
        $.getJSON('http://mydomain.com/MyDataService', {
            skip: loadOptions.skip,
            take: loadOptions.take,
            sort: loadOptions.sort ? JSON.stringify(loadOptions.sort) : "",
            filter: loadOptions.filter ? JSON.stringify(loadOptions.filter) : "",
            requireTotalCount: loadOptions.requireTotalCount,
            totalSummary: loadOptions.totalSummary ? JSON.stringify(loadOptions.totalSummary) : "",
            group: loadOptions.group ? JSON.stringify(loadOptions.group) : "",
            groupSummary: loadOptions.groupSummary ? JSON.stringify(loadOptions.groupSummary) : "",
            requireGroupCount: loadOptions.requireGroupCount // added
        }).done(function (result) {
                d.resolve(result.data, { 
                    totalCount: result.totalCount,
                    summary: result.summary,
                    groupCount: result.groupCount // added
                });
            });
        return d.promise();
    }
});

$(function() {
    $("#datadataGridContainer").dxDataGrid({
        dataSource: gridDataSource,
        remoteOperations: {
            groupPaging: true
        }
    });
});
Angular
TypeScript
HTML
import { ..., Inject } from '@angular/core';
import { Http, HttpModule, URLSearchParams } from '@angular/http';
import DataSource from 'devextreme/data/data_source';
import CustomStore from 'devextreme/data/custom_store';
import 'rxjs/add/operator/toPromise';
// ...
export class AppComponent {
    gridDataSource: any = {};
    constructor(@Inject(Http) http: Http) {
        this.gridDataSource = new DataSource({
            load: function (loadOptions) {
                let params: URLSearchParams = new URLSearchParams();
                params.set("skip", loadOptions.skip);
                params.set("take", loadOptions.take);
                params.set("sort", loadOptions.sort ? JSON.stringify(loadOptions.sort) : "");
                params.set("filter", loadOptions.filter ? JSON.stringify(loadOptions.filter) : "");
                params.set("requireTotalCount", loadOptions.requireTotalCount);
                params.set("totalSummary", loadOptions.totalSummary ? JSON.stringify(loadOptions.totalSummary) : "");
                params.set("group", loadOptions.group ? JSON.stringify(loadOptions.group) : "");
                params.set("groupSummary", loadOptions.groupSummary ? JSON.stringify(loadOptions.groupSummary) : "");
                params.set("requireGroupCount", loadOptions.requireGroupCount); // added
                return http.get('http://mydomain.com/MyDataService', {
                                search: params
                            })
                            .toPromise()
                            .then(response => {
                                var json = response.json();
                                // You can process the received data here
                                return {
                                    data: json.data,
                                    totalCount: json.totalCount,
                                    summary: json.summary,
                                    groupCount: result.groupCount // added
                                }
                            });
            }
        });
    }
}
@NgModule({
    imports: [
        // ...
        DxDataGridModule,
        HttpModule
    ],
    // ...
})
<dx-data-grid ...
    [dataSource]="gridDataSource"
    [remoteOperations]="{groupPaging: true}">
</dx-data-grid>
See Also