MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
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_IDThe thread identifier of the session in which the variable is defined.
VARIABLE_NAMEThe variable name, without the leading
@character.VARIABLE_VALUEThe 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.