See the System Administration site search documentation for information about how site search is implemented. This describes re-indexing, a task that can be performed by a WordPress administrator when needed.

Maintaining the search indexes

Each of the search plugins builds indexes, large files that record every occurrence of words in the website and which pages they appear on. For the most part the indexing takes care of itself and needs no attention, but if you have been adding, removing, or changing very many (hundreds of) pages, search performance may be improved by rebuilding the indexes. If you are going to rebuild the indexes, rebuild the Relevansii index first, then rebuild the FacetWP index. Searching will be unavailable on the public website while the indexes are being rebuilt because the first step in rebuilding is to remove the existing index.

• Rebuilding Relevanssi index. In the WordPress Admin choose Settings from the left menu, then Relevansii. Click on the Indexing tab. Do not change the settings. Click on the ‘Build the Index’ red button. The page will display a progress indicator—the process may take 20-30 minutes. Do not leave that web page until the indexing finishes.
• Rebuilding FacetWP index. In the WordPress Admin choose Settings from the left menu, then FacetWP. Do not change the settings. Click on the ‘Re-index’ red button. The page will display a progress indicator. This process is quicker than the Relevansii re-indexing, but do not leave that web page until the indexing finishes.