What is Pressflow?
Pressflow is a derivative of Drupal core providing enhanced performance, scalability, and data integrity.
Pressflow addresses a long-standing problem: high-traffic sites use stable versions of Drupal, and stable versions of Drupal are generally ineligible for enhancements to solve performance bottlenecks discovered after widespread deployment.
The Strategy
Leveraging Four Kitchens' industry-leading experience in scaling high-traffic, Drupal-based sites, Pressflow integrates the most popular enhancements to Drupal core into a single deployable package. All enhancements made to Drupal core undergo unit testing by the Four Kitchens team prior to release.
Is Pressflow a fork?
Like Drupal, Pressflow is free, open-source software released under the GNU General Public License, version two and later, as published by the Free Software Foundation.
Like Ubuntu, Pressflow leverages the success of an existing popular open-source, free software package with enhancements targeting a specific user set. Releases of Pressflow correspond to Drupal core releases and maintain module and theme compatibility. Following each Drupal core release, Pressflow is "reset," and all enhancements undergo review.
Pressflow is not focused on quick deployment of Drupal with a packaged set of contributed modules selected to provide broad capabilities. Instead, Pressflow focuses on the complementary issue of performance and scalability on large-scale, commercial deployments.
Requirements
Pressflow Core 5 and 6 require PHP 5.2 and MySQL 5. Because Pressflow Core supports a narrower configuration range than Drupal, it can integrate enhancements that would be incompatible with Drupal's current support for PHP 4, MySQL 4.1, and PostgreSQL. As Drupal's configuration requirements improve, enhancements unique to Pressflow Core may be integrated into Drupal. Indeed, some enhancements in Pressflow Core 5 are already integrated into Drupal 6.
