Automatic post deletion

Question

I've built a system where I have 2 options - lifespawn of draft and lifespawn of published post (integer which marks days).

If post is being published, exact date-time of publish is saved as postmeta, also lifespawn is added to that time and that value is saved to database as expiration date-time, same thing with draft (a.k.a when post is being saved).

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My current system is ran like this:

• I've set up a server cron which runs at night in every 24h

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• All published posts are being queried
• Publish date-time metadata is retrieved from database in while loop
• That time is compared with current time in if statement
• If time has passed, change post status to draft

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• All draft posts are being queried
• Draft date-time metadata is retrieved from database in while loop
• That time is compared with current time in if statement
• If time has passed, delete post
• All attached images to the post are also queried and deleted

Im super worried that this system / server fails hard if posts amount is 10 000 - 15 000 or even few thousand. It's important that posts (especially published) that has exceeded the time, are taken down.

What other options do I have?

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Ideas:

• Trigger the date-time "check" for certain amount of older posts in random queries that users do anyway? - longer loading times for users..
• Trigger the date-time "check" if single-post is being visited and do it one-by-one? - queries still retrieve and echo posts if people are quering it in exact same time which leads to 404s and disappointment.
• Somehow split all posts and do it in chunks? - I could use 'offset' to split posts to groups and do it in smaller chunks but it doesn't work if page_per_page is set to -1

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Update:

I've listened your advices and I've tried to query by "expiry date":

• It seems to work.. I changed the cronjob interval and give it a try for few rounds
• Is there a workarounds for formating date? if statement doesn't seem to work otherwise
• Almost same code for drafts, only that I delete draft if time is up
• I also imagine this would be better to run in every 1 hour to avoid big amounts, right?

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//Current date-time
$now = date( 'Y-m-d H:i:s' ); //Let's say it's 2015-12-24 21:00:00 (9PM)

//Get all published posts that are over the deadline
$published_posts = new WP_Query( array(
    'posts_per_page'    => -1,
    'post_type'         => 'my-post',
    'post_status'       => 'publish',
    'meta_query' => array(
        array(
            'key'     => 'post_publish_deadline', //string e.g 2015-12-24 15:00:00 (3PM)
            'value'   => $now,
            'type'    => 'DATETIME',
            'compare' => '<=',
        )
    )
));

while( $published_posts->have_posts() ) {
    $published_posts->the_post();

//Get postmeta deadline and format it for if statement
$publish_deadline = get_post_meta( get_the_ID(), 'post_publish_deadline', true );
//If statement doesn't seem to work without this step
$format_publish_deadline = date( 'Y-m-d H:i:s', strtotime( $publish_deadline ) );

//Check if it exists just in case
if( !empty( $format_publish_deadline ) ) {

     //Additional check if time for that guy is over just in case
     if( $format_publish_deadline < $now ) {

         //Change post status to draft
         wp_update_post( array( 'ID' => get_the_ID(), 'post_status' => 'draft' ) );

         //Get lifespawn option
         $draft_to_delete_lifespawn = $my_option[ 'draft-lifespawn' ];   

         //Build a new draft expiration date-time -> now + lifespawn in hours
         $draft_deadline = date( 'Y-m-d H:i:s', strtotime( $now . ' + ' . $draft_to_delete_lifespawn . ' hours' ) );            

         //Save new draft expiration date-time
         update_post_meta( $post->ID, 'post_draft_deadline', $draft_deadline );
     }
}

} //END while
wp_reset_postdata();

Answer 1

You can improve by storing the "expiry" time of post as a meta instead of the publish time. This way you can query for posts with meta which is smaller then the current time and draft them, no need to loop over all posts.

Drawback is that you will have to decide how to handle changes to lifespawn time, just ignore this edge case or adjust all posts.