As we scale out a variety of services with Redis, it’s not uncommon to run into situations
where sharding our data isn’t enough, where the types of queries we need to execute
require more work than just setting or fetching a value. In this section, we’ll
discuss one problem that’s trivial to scale out, and two problems that take more work.
The first problem that we’ll scale out is our search engine from chapter 7, where
we have machines with enough memory to hold our index, but we need to execute
more queries than our server can currently handle.