How to read large worksheets from large Excel files (27MB+) with PHPExcel?

It is possible to read a worksheet in “chunks” using Read Filters, although I can make no guarantees about efficiency.

$inputFileType="Excel5";
$inputFileName="./sampleData/example2.xls";


/**  Define a Read Filter class implementing PHPExcel_Reader_IReadFilter  */
class chunkReadFilter implements PHPExcel_Reader_IReadFilter
{
    private $_startRow = 0;

    private $_endRow = 0;

    /**  Set the list of rows that we want to read  */
    public function setRows($startRow, $chunkSize) {
        $this->_startRow    = $startRow;
        $this->_endRow        = $startRow + $chunkSize;
    }

    public function readCell($column, $row, $worksheetName="") {
        //  Only read the heading row, and the rows that are configured in $this->_startRow and $this->_endRow
        if (($row == 1) || ($row >= $this->_startRow && $row < $this->_endRow)) {
            return true;
        }
        return false;
    }
}


echo 'Loading file ',pathinfo($inputFileName,PATHINFO_BASENAME),' using IOFactory with a defined reader type of ',$inputFileType,'<br />';
/**  Create a new Reader of the type defined in $inputFileType  **/

$objReader = PHPExcel_IOFactory::createReader($inputFileType);



echo '<hr />';


/**  Define how many rows we want to read for each "chunk"  **/
$chunkSize = 20;
/**  Create a new Instance of our Read Filter  **/
$chunkFilter = new chunkReadFilter();

/**  Tell the Reader that we want to use the Read Filter that we've Instantiated  **/
$objReader->setReadFilter($chunkFilter);

/**  Loop to read our worksheet in "chunk size" blocks  **/
/**  $startRow is set to 2 initially because we always read the headings in row #1  **/

for ($startRow = 2; $startRow <= 240; $startRow += $chunkSize) {
    echo 'Loading WorkSheet using configurable filter for headings row 1 and for rows ',$startRow,' to ',($startRow+$chunkSize-1),'<br />';
    /**  Tell the Read Filter, the limits on which rows we want to read this iteration  **/
    $chunkFilter->setRows($startRow,$chunkSize);
    /**  Load only the rows that match our filter from $inputFileName to a PHPExcel Object  **/
    $objPHPExcel = $objReader->load($inputFileName);

    //    Do some processing here

    $sheetData = $objPHPExcel->getActiveSheet()->toArray(null,true,true,true);
    var_dump($sheetData);
    echo '<br /><br />';
}

Note that this Read Filter will always read the first row of the worksheet, as well as the rows defined by the chunk rule.

When using a read filter, PHPExcel still parses the entire file, but only loads those cells that match the defined read filter, so it only uses the memory required by that number of cells. However, it will parse the file multiple times, once for each chunk, so it will be slower. This example reads 20 rows at a time: to read line by line, simply set $chunkSize to 1.

This can also cause problems if you have formulae that reference cells in different “chunks”, because the data simply isn’t available for cells outside of the current “chunk”.