WordPress SE 71248: Delete revisions on post publish

wpse71248-del-revisions.php

<?php
/**
 * Plugin Name: WPSE71248 Delete Revions on Publish Posts
 * Plugin URI:  http://wordpress.stackexchange.com/questions/71248/
 * Description: 
 * Version:     1.0.0
 * Author:      Frank Bültge
 * Author URI:  http://bueltge.de
 * License:     GPLv3
 */

! defined( 'ABSPATH' ) and exit;

add_action( 'publish_post', 'fb_remove_revisions' );

function fb_remove_revisions( $post_id = FALSE ) {
	
	$post_id = (int) $post_id;
	
	$revisions = '';
	// Get the revisions
	$revisions = new WP_Query( array(
		'post_status'    => 'inherit',
		'post_type'      => 'revision',
		'showposts'      => -1,
		'posts_per_page' => -1,
		'post_parent'    => $post_id
	) );
	
	if ( empty( $revisions ) )
		return $post_id;

	// Remove the revisions the non-core-way
	global $wpdb;
	foreach ( $revisions->posts as $revision ) {
		$query = $wpdb->prepare(
			"
			DELETE FROM $wpdb->posts 
			WHERE ID = %d
			AND post_parent = %d
			",
			$revision->ID, 
			$post_id
		);
		$wpdb->query( $query );
	}
	
	return $post_id;
}