Manual:Objectcache table

Objectcache table is used for a few generic cache operations if not using Memcached. Its content can be deleted and excluded from backups as it will be regenerated when needed.

describe objectcache; +-++--+-+-+---+ +-++--+-+-+---+ +-++--+-+-+---+
 * Field  | Type           | Null | Key | Default | Extra |
 * keyname | varbinary(255) |     | PRI |         |       |
 * value  | mediumblob     | YES  |     | NULL    |       |
 * exptime | datetime      | YES  | MUL | NULL    |       |

DESCRIBE objectcache; in MediaWiki 1.8 gives the following: +-++--+-+-+---+ +-++--+-+-+---+ +-++--+-+-+---+
 * Field  | Type       | Null | Key | Default | Extra |
 * keyname | char(255) | NO   | PRI | NULL    |       |
 * value  | mediumblob | YES  |     | NULL    |       |
 * exptime | datetime  | YES  | MUL | NULL    |       |

+-++--+-+-+---+ +-++--+-+-+---+ +-++--+-+-+---+
 * Field  | Type       | Null | Key | Default | Extra |
 * keyname | char(255) | NO   | PRI | NULL    |       |
 * value  | mediumblob | YES  |     | NULL    |       |
 * exptime | datetime  | YES  | MUL | NULL    |       |

+-+-+--+-+-+---+ +-+-+--+-+-+---+ +-+-+--+-+-+---+
 * Field  | Type            | Null | Key | Default | Extra |
 * keyname | varbinary(255) | NO   | PRI | NULL    |       |
 * value  | mediumblob      | YES  |     | NULL    |       |
 * exptime | datetime       | YES  | MUL | NULL    |       |

+-++--+-+-+---+ +-++--+-+-+---+ +-++--+-+-+---+
 * Field  | Type       | Null | Key | Default | Extra |
 * keyname | char(255) | NO   | PRI | NULL    |       |
 * value  | mediumblob | YES  |     | NULL    |       |
 * exptime | datetime  | YES  | MUL | NULL    |       |