Manual:querycache table

The querycache table is used for caching expensive grouped queries. This table is populated with the updateSpecialPages.php maintenance script.

A key name, generally the base name of the special page.

Some sort of stored value. Sizes, counts...

Target namespace. Used in conjunction with qc_title.

Target title. Used in conjunction with qc_namespace.

DESCRIBEquerycache;

+--------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+------------------+------+-----+---------+-------+
| qc_type | varbinary(32) | NO | MUL | NULL | |
| qc_value | int(10) unsigned | NO | | 0 | |
| qc_namespace | int(11) | NO | | 0 | |
| qc_title | varbinary(255) | NO | | | |
+--------------+------------------+------+-----+---------+-------+

DESCRIBEquerycache;

+--------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| qc_type | varbinary(32) | NO | MUL | NULL | |
| qc_value | int(10) unsigned | NO | | 0 | |
| qc_namespace | int(11) | NO | | 0 | |
| qc_title | char(255) binary | NO | | NULL | |
+--------------+---------------------+------+-----+---------+-------+

DESCRIBEquerycache;

+--------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| qc_type | char(32) | NO | MUL | NULL | |
| qc_value | int(5) unsigned | NO | | 0 | |
| qc_namespace | int(11) | NO | | 0 | |
| qc_title | char(255) binary | NO | | NULL | |
+--------------+---------------------+------+-----+---------+-------+

DESCRIBEquerycache;

+--------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| qc_type | char(32) | NO | MUL | NULL | |
| qc_value | int(5) unsigned | NO | | 0 | |
| qc_namespace | tinyint(2) unsigned | NO | | 0 | |
| qc_title | char(255) binary | NO | | NULL | |
+--------------+---------------------+------+-----+---------+-------+

SHOWINDEXINquerycache;

+------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| querycache | 1 | qc_type | 1 | qc_type | A | 0 | NULL | NULL | | BTREE | | |
| querycache | 1 | qc_type | 2 | qc_value | A | 0 | NULL | NULL | | BTREE | | |
+------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

• MediaWiki database tables
• MediaWiki database tables that lack a primary key