TPC! Memory Usage released!

The very first version of TPC! Memory Usage has been released to the public, and we received WordPress approval to be placed in the plugin directory.  TPC! Memory Usage allows WordPress administrators to track current and peak memory usage.  It’s an extremely useful tool that can help any admin, especially those who use plugins, language files, and other modifications.

The WordPress $wpdb class explained

The WordPress MySQL database class is quite powerful.  This database class can be used for other projects with some very simple modifications, and is actually based on/borrowed from another project called ezSQL by Justin Vincent.

The WordPress database class code is located in <WordPress root>/wp-includes/wp-db.php.  The $wpdb object is created at the very bottom using the following lines of code (comments removed):

if ( ! isset($wpdb) ) {
	$wpdb = new wpdb(DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);
}

Below, I listed a few of the main functions in the $wpdb object.  These functions will help make your job easier when creating plugins and extending the WordPress core, or even working on a completely different project.  I did not include functions used for debugging/error reporting, as that could easily be its own lesson.

  • set_prefix($prefix) — used to set table prefix for WordPress tables, can be used to override prefix at any time.
  • prepare($query) — safely prepares an SQL query for execution with sprintf()-like syntax.
  • query($query) — perform a MySQL database query with current connection
  • insert($table, $data, $format) — insert a row into a table via arrays.
  • update($table, $data, $where, $format, $where_format) — update a row in a table via arrays.
  • get_var($query, $x, $y) — retrieve a single variable from the database.
  • get_row($query, $output, $y) — retrieve a single row from the database.
  • get_col($query, $x) — retrieve a single column from the database in array format.
  • get_results($query, $output) — retrieve SQL result set from database… one or more rows.
/**
 * Insert a new option into the $wpdb->options table.
 * @uses $wpdb WordPress Database Object
 */
$wpdb->insert( $wpdb->options, array('option_name', 'new_option_key', 'option_value' => 'New Option Value', 'autoload' => 'yes') );

/**
 * Update an existing option in the $wpdb->options table.
 * @uses $wpdb
 */
$wpdb->update( $wpdb->options, array('option_value' => 'Newer Option Value'), array('option_name' => 'new_option_value') );

/**
 * Get a single post_id from the $wpdb->postmeta database.
 *
 * The $wpdb->prepare() function ensures that the query is
 * safe for use in the database.  The %d refers to an integer
 * and is replaced by $post_ID in a way that makes it query-safe.
 * The %s refers to a string and is also escaped.
 *
 * @uses $wpdb
 */
$post_id = $wpdb->get_var( $wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE post_id = %d AND meta_key = 'enclosure' AND meta_value LIKE (%s)", $post_ID, $url . '&') );

/**
 * Delete a record from the $wpdb->options database.
 * @uses $wpdb
 */
$wpdb->query("DELETE FROM $wpdb->options WHERE option_name = '$name'");

Feel free to leave comments and ideas on what could make this tutorial better or clearer.

Optimize your WordPress 2.8.4 installation

Large traffic spikes can put an enormous amount of strain on the typical web server, especially low-level hosting plans.  These often occur after appearing on the front page of a social media site (Digg).  While WordPress is well-equipped and can handle these requests, it was designed to be a quick easy install, and is not fully optimized out-of-the-box.  WordPress can be used for high traffic sites, but some features should be implemented to keep your web server running smoothly, and also as a precautionary measure for smaller sites.

Use WP Minify

WP Minify will consolidate and minify and compress JS and CSS files, reducing the number of HTTP requests and decreasing the overall size of the downloaded file.

Use WP Super Cache

WP Super Cache generates static HTML files based on your blog/site content and serves that instead of processing the PHP scripts each time someone visits the site.  This drastically speeds up most WordPress installations.

Remove unnecessary database queries

Themes are built so that they can be applied to mostly any WordPress installation, though chances are you will initially set the title and description and leave them the same.  A typical theme will contain the following lines of code within the header.php file:

<title><?php wp_title('&laquo;', true, 'right'); ?> <?php bloginfo('name'); ?></title>
<link rel="stylesheet" href="<?php bloginfo('stylesheet_url'); ?>" type="text/css" media="screen" />
<link rel="pingback" href="<?php bloginfo('pingback_url'); ?>" />

The aforementioned bloginfo() functions can be replaced with static values, which will prevent the overhead from PHP and any additional database queries. For example, bloginfo(‘name’) could be replaced with My Blog Name. You’ll want to check the other theme files too.

Use Google FeedBurner

Using Google’s feed service will help reduce the load on your server.  It basically works like this:

  1. User visits your feed URL.
  2. User is redirected to the Google feed URL by the WordPress FeedBurner plugin.
  3. Content is served from their servers instead of yours.
  4. …also has the added bonus of including MANY other features, including e-mail subscriptions, formatting for every major RSS platform, pinging, etc.

Install and use Google Gears

WordPress comes with Google Gears support, an application that allows files to be stored locally. Google Gears is integrated with newer versions of Google Chrome, Mozilla Firefox, and Internet Explorer.  While this won’t speed up the front-end of the site, it will reduce the number of HTTP requests on the back-end, drastically speeding up the administration panels, and indirectly helping to reduce the overall load on the server.

Remember, WordPress uses their own software on wordpress.com to serve content to over 170,000 bloggers and many, many more visitors.  This is proof that WordPress works at the enterprise level, although they have very advanced servers and configurations in order to achieve this.  While the average person does not have a need for that sort of environment, some tweaking should still be done to keep server loads down, and keep our carbon footprint at a minimum.