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MySQL 8.0 Reference Manual  /  ...  /  Performance Schema User-Defined Variable Tables

26.12.10 Performance Schema User-Defined Variable Tables

The Performance Schema provides a user_variables_by_thread table that exposes user-defined variables. These are variables defined within a specific session and include a @ character preceding the name; see Section 9.4, “User-Defined Variables”.

The user_variables_by_thread table contains 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.