A query language is a powerful tool that enables developers to communicate with databases in a way that is both efficient and effective. It enables developers to retrieve, insert, update, and delete data from a database using a set of commands and syntax specific to the database management system being used. For example, SQL (Structured Query Language) is a widely used query language for relational databases, enabling developers to perform operations like selecting specific data from a table, filtering data based on certain conditions, and joining data from multiple tables.
In the context of time-series databases, a query language like PromQL enables developers to retrieve and manipulate time-series data, enabling them to perform tasks such as aggregating data over time and filtering based on specific criteria. For instance, a developer might use PromQL to retrieve the average CPU utilization of a set of servers over the past 24 hours and generate a graph to visualize the data.