Preprocessor Modes 

The preprocessors can run in the following different modes:

·        search mode

The preprocessor only preprocesses search queries. In this mode the preprocessor runs on the slave hosts by default.

·        index mode

The preprocessor only preprocesses documents. In this mode the preprocessor runs on the master hosts by default.

·        any mode

The preprocessor's tasks are not restricted.

The modes merely define preferences for the distribution of tasks for the preprocessors. If necessary, a preprocessor carries out all tasks regardless of its mode. For example, in certain circumstances a preprocessor that runs in index mode also processes search queries. This behavior increases the availability of the system, because in principle all preprocessors are able to carry out all tasks.