JQL Tricks plugin enhances the search functionality in Jira Datacenter by adding a set of useful JQL Functions for JIRA 4.x+. Those include simple JQL functions to complex ones.
It has the option to limit the plugin functionality to selected groups and/or limit the individual functions to selected projects.
The plugin also introduces a JQL cache of configurable delay for better performance. The default delay is 120 seconds. Follow the documentation to install and configure the plugin.
Following are the list of functions included. Please click on the linked pages for full syntax of functions, description of the functions and sample queries.