bodi0`s Easy cache

ਅਕਸਰ ਪੁੱਛੇ ਜਾਂਦੇ ਸਵਾਲ

Why WordPress® pages need to be cached?

Briefly explanation, according Wikipedia, in computer science, a cache (pronounced /kash/) is a collection of data, which duplicates original values, stored elsewhere or computed earlier, where the original data is expensive to fetch (owing to longer access time) or to compute, compared to the cost of reading the cache. In other words, a cache is a temporary storage area, where frequently accessed data can be stored for rapid access. Once the data is stored in the cache, it can be used in the future by accessing the cached copy rather than re-fetching or recomputing the original data.

WordPress® is a database-driven publishing platform. That means you have all these great tools on the back-end of your site to work with, but it also means that every time a Post/Page/Category is accessed on your site, dozens of connections to the database have to be made and literally thousands of PHP routines run in harmony behind-the-scenes to make everything dance. The problem is, for every request, that a browser sends to your site, all of these routines and connections have to be made (yes, every single time). This can be very system resource consuming, which actually leads to slowdowns of your website.

In most cases, the big part of the content on your site remains unchanged for at least a couple of minutes, or maybe an hour at a time.
If you’ve been using WordPress® for period of time, you’ve probably noticed that (on average) your site does not
load as fast as it was by initial installation. All of the above is the reason for this.

Where are the cache files stored on my server?

The cache files are stored in a sub-folder of path your choice, by default this is sub-folder, named < cached > inside the default WordPress ‘uploads’ folder. This folder needs to remain writable and accessible (i.e. with permissions set to 0755 or higher).
Inside the < cached > folder Easy cache stores all snapshots as files with names <SHA1>.cache (file name is constructed as an SHA1 hash of the requested URL).
You can remove all cached files from the Administration panel in order to revoke caching mechanism to rebuild the cache upon next post/page access again.

See also: Settings -› Easy cache -› Cache folder path for further details.

Is there a need to modify my current theme in order caching to work correctly?

Maybe. Make sure the call to wp_footer(); function is at the very bottom in your theme’s footer.php file, right before closing < /body> tag. Otherwise contents after wp_footer(); may be not included in generated cache file (i.e. these contents will be most probably scripts or style-sheets, so it is important to check this out).

Will comments or any other dynamic parts of my blog update immediately?

It depends on your configuration of Easy cache. There is an automatic cache expiration system, which runs through WordPress® behind-the-scene, according to your Cached file expires setting (see: Settings -› Easy cache -› Cached file expires after and Settings -› Easy cache -› Rebuild cached file on page/post/comment update). The default value of 30 minutes is suitable for most cases. If you don’t update your site too often, you could set this to 240 minutes (which is 4 hours) or longer. The longer the cache expiration time is, the greater your performance gain. Alternatively, the shorter the expiration time, the fresher everything will remain on your site, but at cost of slowdowns.

Can I exclude given pages or posts from being cached?

Yes, navigate to Settings -› Easy cache -› Exclude pages/posts from caching and select desired items. You can also include/exclude all search queries in your blog from being cached, it will be useful if you have huge amount of traffic, generated by searches to disable search queries exclusion.

See also: Settings -› Easy cache -› Exclude search queries from caching: for further details.

How to verify that Easy cache is working?

First of all, make sure you are NOT logged-in. Then navigate to your site like a normal visitor would. Right-click on any page (choose View Page Source), then scroll to the very bottom of the document. At the bottom, you’ll find comments that show Easy cache statistics and information. You should also notice that page-to-page navigation is very fast, compared to what you experienced prior to installing Easy cache.

Is there any further optimization of saved cache file for speed improvement?

Yes, cached file can be minified (cleaned) and then saved to disk, in typical scenario this process will reduce cache file size between 6 and 12%, which also means, that your visitors will open pages 6 to 12% faster (with given equal conditions).
Remark: minifying is applied to generated HTML file and, optionally, to included CSS files, no JavaScript minification / merge is done. Combining of all CSS resources reduces the CSS resource requests made to the web server to only one (minifiying and combining Google web fonts CSS links, also other external links is also possible, although is sometimes pointless), the minification reduces the file size between 5 and 50%, depending on how structured is the CSS file itself.

See Settings -› Easy cache -› Minify saved cache file for details and Settings -› Easy cache -› Minify and combine CSS files.

Why I need to minify my CSS files and how the CSS minification and combination process works?

Pages that refer to multiple CSS or JavaScript files often suffer from slower page loads, due to the browser requesting each file individually. Many browsers also are limited to a few simultaneous requests per domain. The wait for a series of requests and the transfer of unoptimized files can dramatically reduce the client-side performance of your site.

Insert absolute URL (valid URL according RFC 2396) of CSS files in sequence of their appearance in non-cached page for minification and combination. This process will reduce the number and size of HTTP requests to your server. The CSS files will be merged as single cached CSS resource file, named_css.min.css and saved in your current theme’s folder.

This file will be included in every cached file, old links will be removed.

Important:
Make sure that any URL inside the original CSS code is abosulte, not relative (otherwise you will have missing backgrounds). Also make sure you type the URL of files you want to combine and minify exactly as it is in your original page / post (for example some stylesheets links may have dynamic content attached to them, like: http://www.example.com/color.php?ver=1.2), otherwise minification and combination will not work correctly. If you modify the original CSS files, remember to save settings here in order to re-generate cached CSS resource file.

Why there is separate cache expire setting for search results?

The separate setting is related to caching of search quesries. Sometimes we want to have fresher information in search results (although the results will link to the cached pages/posts), so setting this value lower than the global cache expire time will give the desired outcome. The value is again in minutes.

See Settings -› Easy cache -› Search queries cache expire after for details

What is the purpose of Statistics section?

It gives you technical information about the caching mechanism and server load. This is useful if you want to track more precisely what’s going on your server and on your website.

Is there any PHP/Web server requirements in order this plugin to work?

Only one. The minimum requirement is that the version of PHP is 5.2.4 or later with ‘allow_url_fopen’ setting set to ‘On’ (this is because of the CSS minification and combination).
No other special requirement about the structure of your permalinks, .htaccess file, memory limits or free space on your server. Of course the more, the better for the latter two.

I have a mobile theme from WordPress® Jetpack module, should I do something in order caching to work?

The plugin detects if you have installed the Jetpack from WordPress® mobile theme and it detects if your website is visited by a mobile device. However it is highly recommended to skip caching for mobile pages/posts, otherwise your website visitors may see a mix of the mobile pages/posts and desktop pages/posts. Skipping the caching mechanism for mobile version of your website is necessary, because the Jetpack module by WordPress.com provides his own caching procedure.

Why should I donate to this plugin?

Well, the main purpose of caching mechanism is to save your visitors time and bandwidth, which transfers of saving your money. By reducing the load times you actually economize your resources and provide your visitors better experience, so I won’t mind if you buy me a beer if you are happy about that. Check the ‘Donate’ button for more info.