Using Painless for advanced transform configurations
As we have seen in many of the previous sections, the built-in pivot and aggregation options allow us to analyze and interrogate our data in various ways. However, for more custom or advanced use cases, the built-in functions may not be flexible enough. For these use cases, we will need to write custom pivot and aggregation configurations. The flexible scripting language that is built into Elasticsearch, Painless, allows us to do this.
In this section, we will introduce Painless, illustrate some tools that are useful when working with Painless, and then show how Painless can be applied to create custom Transform configurations.
Introducing Painless
Painless is a scripting language that is built into Elasticsearch. We will take a look at Painless in terms of variables, control flow constructs, operations, and functions. These are the basic building blocks that will help you develop your own custom scripts to use with transforms...