Data About Data

• 当创建一个Table时，DB Server会自动记录以下的信息

  • Table name
  • Table storage information (tablespace, initial size, etc.)
  • Storage engine
  • Column names
  • Column data types
  • Default column values
  • not null column constraints
  • PRIMARY KEY columns
  • PRIMARY KEY names
  • Name of primary key index
  • Index Names
  • Index types(B-tree, bitmap)
  • Indexed columns
  • Index column sort order (ascending or descending)
  • Index storage information
  • Foreign key name
  • Foreign key columns
  • Associated table/columns for foreign keys.

• 几种不同的Metadata存储方式

  • 一堆VIEW
  • 一系列系统存储的进程(system-stored procudures)
  • 一个特殊的database information_schema