Manual:redirect table

A target is broken into four parts: interwiki prefix (should be empty for a regular redirect), namespace, title and fragment.

Contains the page_id of the source page.

Contains the number of the target's Namespace .

Contains the sanitized title of the target page. It is stored as text, with spaces replaced by underscores.

This field is not empty only if an interwiki prefix is used: #REDIRECT [[prefix:…]] (a prefix such as "w:" for Wikipedia, or an interlanguage link prefix such as "nl:" for Dutch, but not both). In this case a redirect is not visible in Special:WhatLinksHere (even if the target lies in the same wiki), rd_namespace is always 0 and rd_title may contain a possible namespace prefix, but rd_fragment may be non-NULL.

Contains the target's fragment ID if present (see also bugzilla:218), otherwise is NULL.

DESCRIBE redirect;

+--------------+------------------+------+-----+---------+-------+
| Field        | Type             | Null | Key | Default | Extra |
+--------------+------------------+------+-----+---------+-------+
| rd_from      | int(10) unsigned | NO   | PRI | 0       |       |
| rd_namespace | int(11)          | NO   | MUL | 0       |       |
| rd_title     | varbinary(255)   | NO   |     |         |       |
| rd_interwiki | varbinary(32)    | YES  |     | NULL    |       |
| rd_fragment  | varbinary(255)   | YES  |     | NULL    |       |
+--------------+------------------+------+-----+---------+-------+

DESCRIBE redirect;

+--------------+---------------------+------+-----+---------+-------+
| Field        | Type                | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| rd_from      | int(10) unsigned    | NO   | PRI | 0       |       |
| rd_namespace | int(11)             | NO   | MUL | 0       |       |
| rd_title     | varchar(255) binary | NO   |     | NULL    |       |
+--------------+---------------------+------+-----+---------+-------+

DESCRIBE redirect;

+--------------+---------------------+------+-----+---------+-------+
| 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) binary | NO   |     | NULL    |       |
+--------------+---------------------+------+-----+---------+-------+

SHOW INDEX IN redirect;

+----------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table    | Non_unique | Key_name    | Seq_in_index | Column_name  | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+----------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| redirect |          0 | PRIMARY     |            1 | rd_from      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| redirect |          1 | rd_ns_title |            1 | rd_namespace | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| redirect |          1 | rd_ns_title |            2 | rd_title     | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| redirect |          1 | rd_ns_title |            3 | rd_from      | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+----------+------------+-------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+---------------+