29.12.10 Performance Schema User-Defined Variable Tables (original) (raw)

29.12.10 Performance Schema User-Defined Variable Tables

The Performance Schema provides auser_variables_by_thread table that exposes user-defined variables. These are variables defined within a specific session and include a @ character preceding the name; seeSection 11.4, “User-Defined Variables”.

The user_variables_by_thread table has these columns:

• THREAD_ID
  The thread identifier of the session in which the variable is defined.
• VARIABLE_NAME
  The variable name, without the leading @ character.
• VARIABLE_VALUE
  The variable value.

The user_variables_by_thread table has these indexes:

• Primary key on (THREAD_ID,VARIABLE_NAME)

TRUNCATE TABLE is not permitted for the user_variables_by_thread table.