Manual:Redirect table

Contains for each page that is currently a redirect (i.e., not for old revisions which are redirects) the id of the source page, the target namespace number, and the target page title without namespace.

The target page may or may not exist.

DESCRIBE mw_redirect; in version 1.9 gives the following: mysql> describe mw_redirect; +--+-+--+-+-+---+ +--+-+--+-+-+---+ +--+-+--+-+-+---+ 3 rows in set (0.02 sec)
 * Field       | Type            | Null | Key | Default | Extra |
 * rd_from     | int(8) unsigned | NO   | PRI | 0       |       |
 * rd_namespace | int(11)        | NO   | MUL | 0       |       |
 * rd_title    | varchar(255)    | NO   |     | NULL    |       |