Manual:Querycachetwo table

querycachetwo is a table used for caching expensive grouped queries that need two links (for example double-redirects).

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

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

qcc_namespace
Target namespace. Used in conjunction with gcc_title.

qcc_title
Target title. Used in conjunction with gcc_namespace.

qcc_namespacetwo
Target namespace2. Used in conjunction with gcc_titletwo.

qcc_titletwo
Target title2. Used in conjunction with gcc_namespacetwo.

Versions
mysql> describe querycachetwo; +--+--+--+-+-+---+ +--+--+--+-+-+---+ +--+--+--+-+-+---+
 * Field           | Type             | Null | Key | Default | Extra |
 * qcc_type        | varbinary(32)    | NO   | MUL | NULL    |       |
 * qcc_value       | int(10) unsigned | NO   |     | 0       |       |
 * qcc_namespace   | int(11)          | NO   |     | 0       |       |
 * qcc_title       | varbinary(255)   | NO   |     |         |       |
 * qcc_namespacetwo | int(11)         | NO   |     | 0       |       |
 * qcc_titletwo    | varbinary(255)   | NO   |     |         |       |

DESCRIBE querycachetwo; in version 1.18 gives the following: +--+-+--+-+-+---+ +--+-+--+-+-+---+ +--+-+--+-+-+---+
 * Field           | Type            | Null | Key | Default | Extra |
 * qcc_type        | binary(32)      | NO   | MUL | NULL    |       |
 * qcc_value       | int(5) unsigned | NO   |     | 0       |       |
 * qcc_namespace   | int(11)         | NO   |     | 0       |       |
 * qcc_title       | binary(255)     | NO   |     | NULL    |       |
 * qcc_namespacetwo | int(11)        | NO   |     | 0       |       |
 * qcc_titletwo    | binary(255)     | NO   |     | NULL    |       |

DESCRIBE querycachetwo; in version 1.12 gives the following: +--+-+--+-+-+---+ +--+-+--+-+-+---+ +--+-+--+-+-+---+
 * Field           | Type            | Null | Key | Default | Extra |
 * qcc_type        | char(32)        | NO   | MUL | NULL    |       |
 * qcc_value       | int(5) unsigned | NO   |     | 0       |       |
 * qcc_namespace   | int(11)         | NO   |     | 0       |       |
 * qcc_title       | char(255)       | NO   |     | NULL    |       |
 * qcc_namespacetwo | int(11)        | NO   |     | 0       |       |
 * qcc_titletwo    | char(255)       | NO   |     | NULL    |       |

DESCRIBE querycachetwo; in version 1.11 gives the following: +--+--+--+-+-+---+ +--+--+--+-+-+---+ +--+--+--+-+-+---+
 * Field           | Type             | Null | Key | Default | Extra |
 * qcc_type        | varbinary(32)    | NO   | MUL | NULL    |       |
 * qcc_value       | int(10) unsigned | NO   |     | 0       |       |
 * qcc_namespace   | int(11)          | NO   |     | 0       |       |
 * qcc_title       | varchar(255)     | NO   |     | NULL    |       |
 * qcc_namespacetwo | int(11)         | NO   |     | 0       |       |
 * qcc_titletwo    | varchar(255)     | NO   |     | NULL    |       |

DESCRIBE querycachetwo; in version 1.9 gives the following: +--+-+--+-+-+---+ +--+-+--+-+-+---+ +--+-+--+-+-+---+
 * Field           | Type            | Null | Key | Default | Extra |
 * qcc_type        | char(32)        | NO   | MUL | NULL    |       |
 * qcc_value       | int(5) unsigned | NO   |     | 0       |       |
 * qcc_namespace   | int(11)         | NO   |     | 0       |       |
 * qcc_title       | char(255)       | NO   |     | NULL    |       |
 * qcc_namespacetwo | int(11)        | NO   |     | 0       |       |
 * qcc_titletwo    | char(255)       | NO   |     | NULL    |       |