MySQL 9.3 Reference Manual Including MySQL NDB Cluster 9.3
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 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.