Recoll indexing can be performed along two main modes:
Periodic (or batch) indexing . recollindex is executed at discrete times. On Unix-like systems, the typical usage is to have a nightly run programmed into your cron file. On Windows, the Task Scheduler can be used to run indexing. In both cases, the Recoll GUI includes a simplified interface to configure the system scheduler.
Real time indexing . recollindex runs permanently as a daemon and uses a file system alteration monitor (e.g. inotify on Unix-like systems) to detect file changes. New or updated files are indexed at once. Monitoring a big file system tree can consume significant system resources.
The choice between the two methods is mostly a matter of preference, and they can be combined by setting up multiple indexes (e.g.: use periodic indexing on a big documentation directory, and real time indexing on a small home directory), or by configuring the index so that only a subset of the tree will be monitored.
The choice of method and the parameters used can be configured from the recoll GUI: → dialog.