Export large rows to Excel document, in small memory footprint

I am using PHPExcel to create an Excel document, using data from a MySQL database. My script must execute in under 512MB of RAM, and I am running into trouble as my export reaches 200k records:

PHP Fatal error: Allowed memory size of...

How can I use PHPExcel to create large documents in as little amount of RAM as possible?

My current code:

            // Autoload c开发者_StackOverflow中文版lasses
    ProjectConfiguration::registerPHPExcel();


    $xls = new PHPExcel();
    $xls->setActiveSheetIndex(0);


    $i = 0; 
    $j = 2; 
            // Write the col names
    foreach ($columnas_excel as $columna) {
        $xls->getActiveSheet()->setCellValueByColumnAndRow($i,1,$columna);
        $xls->getActiveSheet()->getColumnDimensionByColumn($i)->setAutoSize(true);
        $i++;
    }


    // paginate the result from database
    $pager = new sfPropelPager('Antecedentes',50);
    $pager->setCriteria($query_personas);
    $pager->init();
    $last_page = $pager->getLastPage();

    //write the data to excel object
    for($pagina =1; $pagina <= $last_page; $pagina++) {
        $pager->setPage($pagina);
        $pager->init();
        foreach ($pager->getResults() as $persona) {
            $i = 0;
            foreach ($columnas_excel as $key_col => $columnas) {
                $xls->getActiveSheet()->setCellValueByColumnAndRow($i,$j,$persona->getByName($key_col, BasePeer::TYPE_PHPNAME));
                $i++;
            }
            $j++;
        }
    }

    // write the file to the disk
    $writer = new PHPExcel_Writer_Excel2007($xls);
    $filename = sfConfig::get('sf_upload_dir') . DIRECTORY_SEPARATOR . "$cache.listado_personas.xlsx";
    if (file_exists($filename)) {
        unlink($filename);
    }
    $writer->save($filename);

CSV version:

// Write the col names to the file
$columnas_key = array_keys($columnas_excel);
file_put_contents($filename, implode(",", $columnas_excel) . "\n");

//write data to the file
for($pagina =1; $pagina <= $last_page; $pagina++) {                     
        $pager->setPage($pagina);
        $pager->init();
        foreach ($pager->getResults() as $persona) {
            $persona_arr = array();
            // make an array        
            foreach ($columnas_excel as $key_col => $columnas) {
                $persona_arr[] = $persona->getByName($key_col, BasePeer::TYPE_PHPNAME);                 
            }
            // append to the file
            file_put_contents($filename, implode(",", $persona_arr) . "\n", FILE_APPEND | LOCK_EX);             
        }
    }

Still have the problem of RAM when Propel makes requests to the database, it's like Propel, does not release the RAM every time you make a new request. I even tried to create and delete the Pager object in each iteration

Propel has formatters in the Query API, you'll be able to write this kind of code:

<?php
$query = AntecedentesQuery::create()
           // Some ->filter()
           ;
$csv = $query->toCSV();

$csv contains a CSV content you'l be able to render by setting the correct mime-type.

Since it appears you can use a CSV, try pulling 1 record at a time and appending it to your CSV. Don't try to get all 200k records at the same time.

$cursor = mysql_query( $sqlToFetchData );    // get a MySql resource for your query
$fileHandle = fopen( 'data.csv', 'a');       // use 'a' for Append mode

while( $row = mysql_fetch_row( $cursor ) ){  // pull your data 1 record at a time
    fputcsv( $fileHandle, $row );            // append the record to the CSV file
}

fclose( $fileHandle );                       // clean up
mysql_close( $cursor );

I'm not sure how to transform the CSV into an XLS file, but hopefully this will get you on your way.