Documentation Home
MySQL Performance Schema
Related Documentation Download this Excerpt
PDF (US Ltr) - 1.0Mb
PDF (A4) - 1.0Mb
HTML Download (TGZ) - 168.4Kb
HTML Download (Zip) - 186.8Kb


MySQL Performance Schema  /  Performance Schema Table Descriptions  /  Performance Schema User-Defined Variable Tables

10.10 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 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.