Manual:Page props table

Contains properties about pages set by the parser via ParserOutput::setProperty, such as the display title and the default category sortkey. In particular, all double underscore magic words are automatically recorded here. Also, many extensions use this table to store their own data. Note that reparsing a page causes all of its properties to be purged from this table and replaced with the new ones, so this table is not suitable for storing data that can't be regenerated during a reparse.

mysql> describe page_props; +-+---+--+-+-+---+ +-+---+--+-+-+---+ +-+---+--+-+-+---+ 3 rows in set (0,00 sec)
 * Field      | Type          | Null | Key | Default | Extra |
 * pp_page    | int(11)       | NO   | PRI | NULL    |       |
 * pp_propname | varbinary(60) | NO  | PRI | NULL    |       |
 * pp_value   | blob          | NO   |     | NULL    |       |