While engineering, we fix bugs, create new systems, build workflows and establish processes. Our job is to change things. Changing things can involve mistakes that ultimately lead to the failure of a particular system. To learn from these failures, a retrospective is helpful to get to the root of this problem. In the tech industry, a Blameless PostMortem is the right tool for this job.
FOSDEM in Brussels is one of our favorite conferences each year as it fully reflects our love for Free and Open Source software.
For our products, like the trivago [hotel search](https://www.trivago.com/), we are using [Redis](http://redis.io/) a lot. The use cases vary: Caching, temporary storage of data before moving those into another storage or a typical database for hotel meta data including persistence. The main parts of the hotel search are built with PHP and the Symfony Framework for the frontend (web) and Java for the backend part. In this article, we will focus on the collaboration between our PHP application and Redis. Both are running fine, but it was a long and hard way up to the current situation. This is the story of how we learned to use Redis, including our failures and experience.