Personal computing devices store more and more loosely arranged data. Each new method of keeping track of your data supposes that you stop using old methods on this data. One of the more stable interfaces for data access is the filesystem API. However, the standard filesystem semantic provides a fixed and limited set of ways to search for data.

QueryFS is a virtual filesystem for POSIX-like systems that compiles user-supplied queries in various DSLs via translation to Common Lisp code and represents the results as directories. The main current use-case is using it to navigate and process data stored or indexed in PostgreSQL with traditional tools (grep, find, vim etc.)

We show how practical usage of QueryFS looks like and what lies behind this.