The or() and endOr() methods supported by the TaskQuery are very handy and would be great to have them also in all other queries like ProcessInstanceQuery or HistoricProcessInstanceQuery and HistoricTaskInstanceQuery and so on. At the moment you need to queries if you would like to query for an ProcessInstance where one variable OR another is set to a specific value which is from a performance point-of-view very bad.

See also CAM-4972 for the initial ticket for the TaskQuery OR condition