Using Post Meta instead of Transients

post-meta-transients-almost-identical.php

<?php

// Use transients.
if ( false === ( $transient_data = get_transient( 'transient_name' ) ) ) {
    // Regenerate transient.
}

// Use post meta.
if ( false === ( $post_meta_data = get_post_meta(1, 'post_meta_name', true ) ) ) {
    // Regenerate post meta.
}

wp-query-fields-ids-loop.php

<?php

// Query all products and only retrieve post IDs
$args = array('post_type'=>'product', 'posts_per_page' => -1, 'fields' => 'ids', 'no_found_rows' => true, 'update_post_term_cache' => false, 'update_post_meta_cache' => false);
$products_query = new WP_Query($args);

$product_ids = array();
$product_ids = $products_query->posts;  // This is the 'loop'!
wp_reset_postdata();

foreach ($product_ids as $id) {
  // Do stuff
}

wp-query-traditional-loop.php

<?php
$pq_args = array(
            'post_type' => 'product',
            'posts_per_page' => -1,
            'no_found_rows' => true,
            'update_post_term_cache' => false,
            'update_post_meta_cache' => false,
            );

$products_query = new WP_Query($pq_args);

if ( $products_query->have_posts() ) {
    while ( $products_query->have_posts() ) {
        $products_query->the_post();
        // Do stuff
    }
}