How to export all rows from Datatables using Ajax?

Thanks a lot to the user “kevinpo”. He has given the way how all records from jquery datatable to be downloaded as excel when server side processing is On.
Based on his answer, here i have complete export functionality implemented (copy, excel, csv, pdf, print) for server side processing.

inside $(document).ready() define the below function & call this function on action of each export button like below :

/* For Export Buttons available inside jquery-datatable "server side processing" - Start
- due to "server side processing" jquery datatble doesn't support all data to be exported
- below function makes the datatable to export all records when "server side processing" is on */

function newexportaction(e, dt, button, config) {
    var self = this;
    var oldStart = dt.settings()[0]._iDisplayStart;
    dt.one('preXhr', function (e, s, data) {
        // Just this once, load all data from the server...
        data.start = 0;
        data.length = 2147483647;
        dt.one('preDraw', function (e, settings) {
            // Call the original action function
            if (button[0].className.indexOf('buttons-copy') >= 0) {
                $.fn.dataTable.ext.buttons.copyHtml5.action.call(self, e, dt, button, config);
            } else if (button[0].className.indexOf('buttons-excel') >= 0) {
                $.fn.dataTable.ext.buttons.excelHtml5.available(dt, config) ?
                    $.fn.dataTable.ext.buttons.excelHtml5.action.call(self, e, dt, button, config) :
                    $.fn.dataTable.ext.buttons.excelFlash.action.call(self, e, dt, button, config);
            } else if (button[0].className.indexOf('buttons-csv') >= 0) {
                $.fn.dataTable.ext.buttons.csvHtml5.available(dt, config) ?
                    $.fn.dataTable.ext.buttons.csvHtml5.action.call(self, e, dt, button, config) :
                    $.fn.dataTable.ext.buttons.csvFlash.action.call(self, e, dt, button, config);
            } else if (button[0].className.indexOf('buttons-pdf') >= 0) {
                $.fn.dataTable.ext.buttons.pdfHtml5.available(dt, config) ?
                    $.fn.dataTable.ext.buttons.pdfHtml5.action.call(self, e, dt, button, config) :
                    $.fn.dataTable.ext.buttons.pdfFlash.action.call(self, e, dt, button, config);
            } else if (button[0].className.indexOf('buttons-print') >= 0) {
                $.fn.dataTable.ext.buttons.print.action(e, dt, button, config);
            }
            dt.one('preXhr', function (e, s, data) {
                // DataTables thinks the first item displayed is index 0, but we're not drawing that.
                // Set the property to what it was before exporting.
                settings._iDisplayStart = oldStart;
                data.start = oldStart;
            });
            // Reload the grid with the original page. Otherwise, API functions like table.cell(this) don't work properly.
            setTimeout(dt.ajax.reload, 0);
            // Prevent rendering of the full data to the DOM
            return false;
        });
    });
    // Requery the server with the new one-time export settings
    dt.ajax.reload();
};
//For Export Buttons available inside jquery-datatable "server side processing" - End

And for buttons, define like below

"buttons": [{
               "extend": 'copy',
               "text": '<i class="fa fa-files-o" style="color: green;"></i>',
               "titleAttr": 'Copy',                               
               "action": newexportaction
            },
            {
               "extend": 'excel',
               "text": '<i class="fa fa-file-excel-o" style="color: green;"></i>',
               "titleAttr": 'Excel',                               
               "action": newexportaction
            },
            {
               "extend": 'csv',
               "text": '<i class="fa fa-file-text-o" style="color: green;"></i>',
               "titleAttr": 'CSV',                               
               "action": newexportaction
            },
            {
               "extend": 'pdf',
               "text": '<i class="fa fa-file-pdf-o" style="color: green;"></i>',
               "titleAttr": 'PDF',                               
               "action": newexportaction
            },
            {
               "extend": 'print',
               "text": '<i class="fa fa-print" style="color: green;"></i>',
               "titleAttr": 'Print',                                
               "action": newexportaction
            }],

That’s it. Now your download is ready.