Very slow query with meta_query on large database

I have a blog with about 200k posts and each one have 20 custom fields.

I’ve been using WordPress Transients_API to cache queries, in the few cases where it can be used, but it can’t be used in some other queries due to the nature of the blog.

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My blog is http://fixapk.com

There is a problem when accessing applications (single.php).

My code to retrieve the relevant articles using the custom field *’_similar_apps’*, is as follows:

$args = array(
  'showposts' => 10,
  'post_type' => 'post',
  'meta_query' => array(
    'relation' => 'OR',
     array(
       'key' => '_similar_apps',
       'value' => $mainlink,
       'compare' => 'LIKE'
     ),
   ),
);
$q = new WP_Query( $args );

if ( $q->have_posts() ) : while( $q->have_posts() ): $q->the_post();
  // Do something....

But it is very slow.

You can visit following link to open an article and see its speed

http://fixapk.com/chrome-samsung-support-library/

…it takes about 6-10 second to load.

So, how can I optimize queries with meta_query?

Thank you very much!

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1 comment

  1. It is recommended to stick with WP_query for grabbing WordPress posts; but, you can build your own queries directly from the postmeta table, then iterate through the results.

    Depending on the query, this may be faster (Not often; WordPress works hard to make their database queries as fast as they can be).

    global $wpdb;
    $table = $wpdb->prefix . 'the_table_you_want';
    $sql = $wpdb->prepare( 'SELECT id FROM ' . $table . ' WHERE some_field = %s AND another_field = %d;', 'some_value', 42 );
    $results = $wpdb->get_results( $sql );
    
    foreach( $results as $result ):
    
        //do stuff with $result ( it is an object, not an array )       
    
    endforeach;
    

    ALWAYS use prepare when constructing your own queries.