When using the following, I get the CSV button as expected but it only download the first page of data. Is this expected behavior??? This report is very large can have up to 200,000 recs. Also, any tips on tuning this are welcome.

DataTables::create(

    [
        'name' => 'PBHBDetail',
        'dataSource' => function () {
            return $this->src('PBHBDetail')
                ->query($this->params['query_sql']);
        },
        'scope' => $this->params,
        "plugins" => ["Buttons"],
        "options" => [
            "searching" => false,
            "paging" => true,
            "pagingType" => "input",
            "colReorder" => true,
            "order" => [],
            "ordering" => false,
            "pageLength" => 50,
            "bInfo" => false, // remove 'showing x to y of z entries'
            "dom" => 'Bfrtip',
            "buttons" => [
                "copy", "colvis", "csv"
            ]
        ],
        "columns" => \UCSF\DOM\Reports\DivisionRpt\PBHBDetail::determine_columns(),
        "showFooter" => false,
        "serverSide" => true,
        "searchOnEnter" => true,
        "searchMode" => "or",
        "cssClass" => [
            "table" => "table table-striped table-bordered compact",
        ],
    ]);

Thanks, that my next stop.