Example with custom query migrated from Codex

<?php 
$args = array('posts_per_page' = -1);
$my_posts = new WP_Query($args);
if ($my_posts->have_posts()) : while ($my_posts->have_posts()) : $my_posts->the_post(); ?>
<?php the_content(); ?>
<?php endwhile; endif; ?>

// rewind
<?php $my_posts->rewind_posts(); ?>

// new loop
<?php while ($my_posts->have_posts()) : $my_posts->the_post(); ?>
<?php the_content(); ?>
<?php endwhile; ?>