Tracing user-defined functions in a database system

A system includes at least one hardware processor of a computing node and at least one memory storing instructions that cause the at least one hardware processor to perform operations. The operations include instantiating a user code runtime to execute within a sandbox process. The sandbox process configures access by the user code runtime to an operating system (OS) kernel of the computing node. The OS kernel is configured with one or more filtering policies. A determination is performed of whether a system call received by the OS kernel violates the one or more filtering policies. The system call is triggered by at least one operation of the user code runtime. A tracing event is instantiated to trace execution of the system call based on the determination.