Get the number of rows matching a select query with Zend_Db

zend_db_count.php

<?php

class ZdbCountExample
{
    public function doSelect()
    {
        $pageSize = 1000;
        $numPages = ceil($this->count($this->baseSelect()) / $pageSize);

        for ($page = 0; $page <= $numPages; $page++) {
            $data = $this->readPage($this->baseSelect(), $page, $pageSize);
        }
    }

    protected function baseSelect()
    {
        return $this->db
            ->select()
            ->from('a_table')
            ->columns(array('some', 'columns'));
    }

    protected function readPage($select, $page, $pageSize)
    {
        $select->limitPage($page, $pageSize);
        $rs = $this->db->query($select);
        
        return $rs->fetchAll();
    }

    protected function count(Zend_Db_Select $select)
    {
        $select->reset('columns')
               ->columns(array('total_count' => new Zend_Db_Expr('count(*)')));

        $rs = $this->getReadConnection()->fetchRow($select);

        return $rs['total_count'];
    }
}