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Until the mid 90s, spam was a non-issue. It was exciting to get email. The web was also virtually spam-free. Netizens respected one another and everything was very pleasant. Those days are long gone. Fortunately, there are some pretty amazing tools out there for fighting email spam. I use a combination of SpamAssassin on the server side and Thunderbird (with its wonderful built in junkmail filters) on the desktop. I am sent thousands of spam messages a day that I never see thanks to these tools.

But approximately five years ago, a new type of spam emerged which exploited not email but the web. Among this new wave of abuse, my personal favorite, comment spam.

I love getting comments on my blog. I also like reading comments on other blogs. However, it's not practical to simply allow anyone who wants to leave a comment, as within a very short period of time, blog comments will be overrun with spam generated by scripts that exploit sites with permissive comment privileges. To prevent this, most sites require that you log in to post a comment. But this may be too much to ask of someone who just wants to post a quick comment as they pass through. I often come across blog postings which I would like to contribute to, but I simply don't bother because the site requires me to create an account (which I'd likely only use once) before posting a comment. Not worth it. Another common practice is the use of "captchas" which require a user enter some bit of information to prove they are human and not a script. This works fairly well, however, it is still a hurdle that must be jumped before a user can post a comment. And as I've personally learned, captchas, particularly those that are image based, are prone to problems which may leave users unable to post a comment at all.

PHP is an interpreted language. This means that each time a PHP generated page is requested, the server must read in the various files needed and "compile" them into something the machine can understand (opcode). A typical Drupal page requires more than a dozen of these bits of code be compiled.

Opcode cache mechanisms preserve this generated code in cache so that it need only be generated a single time to server hundreds or millions of subsequent requests.

Enabling opcode cache will reduce the time it takes to generate a page by up to 90%.

PHP is known for its blazing speed. Why would you want to speed up your PHP applications even more? Well, first and foremost is the coolness factor. Next, you'll increase the capacity of your current server(s) many times over, thereby postponing the inevitable need to add new hardware as your site's popularity explodes. Lastly, high bandwidth, low latency visitors to your site who are currently seeing page load times in the 1-2 second range will be shocked to find your vamped up site serving up pages almost instantaneously. After enabling opcode cache on my own server, I saw page loads drop from about 1.5 seconds to as low as 300ms. Now that's good fun the whole family can enjoy.

One of the great features of Drupal is its ability to run any number of sites from one base installation, a feature generally referred to as multisites . Creating a new site is just a matter of creating a settings.php file and (optionally) a database to go with your new site. That's it. More importantly, there's no need to set up complicated Apache Virtual hosts, which are a wonderful feature of Apache, but can be very tricky and tedious, especially if you're setting up a large number of subsites.

No worries, there is a solution.

This article explains a practical implementation of a technique outlined in the article "Sharing Drupal tables between databases using MySQL5 Views".

Problem

You have multiple (multisite) Drupal sites and you would like to manage the content for all of these sites through a single interface. Depending on the nature of a given piece of content, you may want the content published on one, several or all of your subsites, but you do not want to have to create copies of the same content for each site.

Solution

Taxonomy plus MySQL5 views. (NOTE: this solution will not work with versions of MySQL prior to 5.)