click_data.use_click_data_in_index (collection.cfg setting)
This option allows control over whether or not click data will be included in the building of indexes. Click data helps to improve relevant results by boosting the ranking of results that many people have clicked on. This value can be set to:
true, if click data should be included in building the index.
false, if click data is not desired.
Note: Setting this option to false will cause all other click data related options to be ignored.