Systems, methods, and apparatus for preventing misuse of searches of a database system are provided. This prevention of misuse of database searches can enable reliable operation of the database system, as an improper query using a regular expression will not shut down or severely affect an application process that provides access to the database system. A thread of the application process determines whether an input character string matches the regular expression. To prevent misuse, a computational effort of the search is tracked, and compared to a threshold value. When the threshold is exceeded, an operation of the thread is exited or stopped.