Manual:$wgDBminWordLen

Details
''' This config var is extremely obsolete and applied only to MediaWiki 1.5 and below running on MySQL 3.x. Nearly everybody today should be looking at  for this issue. '''

Minimum string length that the search engine will search on.


 * The Go function will take you to a page that is an exact match for the name.


 * The Search function will appear to search and give no results.


 * MySQL 3.x : Used to discard words that MySQL will not return any results for. Shorter values configure mysql directly.
 * MySQL 4.x+ : Ignore $wgDBminWordLen and configure mySQL directly.

To configure mySQL, see the mySQL fulltext fine-tuning documentation (4.0/4.1, 5.1).

The only table with a fulltext index in wikimedia is searchindex, so after changing the mySQL configuration and restarting mySQL, issue the command  .

Note
While the effects of the setting were removed in version 1.6, the variable wasn't removed from DefaultSettings until version 1.14 (r41038).