Here is my classification of blocks in the context of caching, or five approaches to caching, and my thoughts on when and how to use them. This covers both full page and block cache.

While infrastructure tuning can result in regular additional costs, it still can only soften the impact of application architecture and algorithms. It is code that stands behind application performance first. That's why it is important to always keep in mind performance implications while customizations and especially extensions development.

The idea of Dublin Magento Developers Meetup came up at the Magento Meetup Ireland 16. That was a result of Magento community willing to have more frequent and more technical meetups, the brilliant technical presentation by Gordon Knoppe following by a quart of Guinness and active communication at Ashton's. :)

Magento 2 CE has built-in Varnish cache invalidation functionality supporting several cache servers and invalidation by tags. This functionality can be easily overlooked because it is not explicit enough, there is even no UI related to it.

Retrieving layered navigation attributes is a useful task that can be required during optimization and implementation of various features. As usual, there is more than one way for achieving the goal. I will start from the most simple and fast approach, and continue with more framework utilization recommended for future maintainability.

There are several ways to achieve the same goal and run multiple websites on different PHP versions simultaneously. In my opinion, the most convenient way to install several PHP versions side-by-side for development purpose is using PHPBrew. As for running multiple php versions on one server, my choice is Apache with FastCGI.

First of all, ensure you have your column in database table, and it is mapped to any field of sales_order table. Don't worry about implications of core table modification. sales_order_grid is index table and is used for order grid rendering speed up. It is designed to store all information required for sales order grid rendering, so custom columns are required to be added to this table.