The subject technology receives, in a computing process, a user defined function, the user defined function including code related to at least one operation to be performed. The subject technology determines by a security manager whether performing the at least one operation is permitted, the security manager determines restrictions, based at least in part on a security policy. The subject technology performs the at least one operation. The subject technology sends a result of the at least one operation to the computing process, where sending the result of the at least one operation utilizes a data transport mechanism that supports a network transfer of columnar data.