Confluence 7.0 and later
The plugin module allows you to hook into the mechanism that Confluence uses to populate its search index. Each time content is created or updated in Confluence, it is passed through a chain of extractors that assemble the fields and data that will be added to the search index for that content.
By writing your own extractor you can add information to the index.
See our Create a search extractor tutorial for a step-by-step example.