The brokenlinks table stored links to articles that don't exist yet. This was used for Special:Wantedpages (which was sometimes disabled), and perhaps for some link caching. It was the twin of the links table.

Beginning with the MediaWiki 1.5 release this table is not used, and can be safely deleted. The contents have been migrated to the pagelinks table on update. Regenerating the pagelinks table always is possible using the rebuildall.php maintenance script.

bl_from stores the cur_id of the article which contains the link, bl_to stores the name (including namespace prefix) of the desired article.

Schema summary

+---------+-----------------+------+-----+---------+-------+
| Field   | Type            | Null | Key | Default | Extra |
+---------+-----------------+------+-----+---------+-------+
| bl_from | int(8) unsigned | NO   | PRI | 0       |       |
| bl_to   | varchar(255)    | NO   | PRI |         |       |
+---------+-----------------+------+-----+---------+-------+

+---------+-----------------+------+-----+---------+-------+
| Field   | Type            | Null | Key | Default | Extra |
+---------+-----------------+------+-----+---------+-------+
| bl_from | int(8) unsigned | NO   |     | 0       |       |
| bl_to   | varchar(255)    | NO   |     |         |       |
+---------+-----------------+------+-----+---------+-------+

Indexes

SHOW INDEX IN brokenlinks;

+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table       | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| brokenlinks |          0 | bl_from  |            1 | bl_from     | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| brokenlinks |          0 | bl_from  |            2 | bl_to       | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
| brokenlinks |          1 | bl_to    |            1 | bl_to       | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
+-------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+