Bits of .NET

⚡ Don’t Let WP_Query Kill Your Database

WP_Query is powerful but dangerous. Bad queries = slow site. Learn best practices for performance.

📝 Do’s and Don’ts

// ❌ DON'T: Query inside loop
while (have_posts()) {
    the_post();
    $related = new WP_Query(['post_type' => 'post', 'posts_per_page' => 5]);
    // Runs 10 times = 10 extra queries!
}

// ✅ DO: Query once, use caching
$related = new WP_Query(['post_type' => 'post', 'posts_per_page' => 50]);
$related_posts = $related->posts;

// ❌ DON'T: Query all posts without limit
$query = new WP_Query(['posts_per_page' => -1]); // Loads everything!

// ✅ DO: Limit results
$query = new WP_Query(['posts_per_page' => 50]);

// ❌ DON'T: No cache for expensive queries
$recent = new WP_Query($args);

// ✅ DO: Cache results with transients
$recent = get_transient('recent_posts');
if (false === $recent) {
    $recent = new WP_Query($args);
    set_transient('recent_posts', $recent, HOUR_IN_SECONDS);
}

🎯 Optimize Query Parameters

$args = [
    'posts_per_page' => 10,
    'no_found_rows' => true,           // Skip pagination calc (faster)
    'update_post_meta_cache' => false, // Skip meta cache (if not needed)
    'update_post_term_cache' => false, // Skip term cache (if not needed)
    'fields' => 'ids',                 // Only get IDs (much faster)
    'cache_results' => true,           // Cache query results
];

// Only get what you need
$ids = get_posts($args); // Returns array of IDs only

// Then get specific post data if needed
foreach ($ids as $id) {
    $title = get_the_title($id);
}

✅ Use wp_reset_postdata()

• Always call wp_reset_postdata() after custom WP_Query loops
• Prevents conflicts with main query
• Use wp_reset_query() if you used query_posts() (avoid query_posts!)