Manual:Querycache table

MediaWiki database layout

querycache table

MediaWiki version:

≥ 1.3

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

Fields

qc_type

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

qc_value

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

qc_namespace

Target namespace. Used in conjunction with qc_title.

qc_title

Target title. Used in conjunction with qc_namespace.

Schema summary

MediaWiki version:

≥ 1.11

DESCRIBE querycache;

+--------------+------------------+------+-----+---------+-------+
| 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   |     |         |       |
+--------------+------------------+------+-----+---------+-------+

MediaWiki version:

1.10

DESCRIBE querycache;

+--------------+---------------------+------+-----+---------+-------+
| 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    |       |
+--------------+---------------------+------+-----+---------+-------+

MediaWiki versions:

1.5 – 1.9

DESCRIBE querycache;

+--------------+---------------------+------+-----+---------+-------+
| 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    |       |
+--------------+---------------------+------+-----+---------+-------+

MediaWiki versions:

1.3 – 1.4

DESCRIBE querycache;

+--------------+---------------------+------+-----+---------+-------+
| 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    |       |
+--------------+---------------------+------+-----+---------+-------+

Indexes

MediaWiki version:

≥ 1.5

SHOW INDEX IN querycache;

+------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| 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      |         |               |
+------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+