Manual:Querycache table

The querycache table is used for caching expensive grouped queries.

This table is populated with the  maintenance script.

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 ns>Special:MyLanguage/Manual:Page table#page_namespace|namespace.

Used in conjunction with qc_title.

qc_title
Target title>Special:MyLanguage/Manual:Page table#page_title|title.

Used in conjunction with qc_namespace.

Schema summary
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    | varchar(255) binary | NO   |     | NULL    |       |

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    |       |

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    |       |

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    |       |