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29.12.14.2 Performance Schema persisted_variables Table

The persisted_variables table provides an SQL interface to the mysqld-auto.cnf file that stores persisted global system variable settings, enabling the file contents to be inspected at runtime using SELECT statements. Variables are persisted using SET PERSIST or PERSIST_ONLY statements; see Section 15.7.6.1, “SET Syntax for Variable Assignment”. The table contains a row for each persisted system variable in the file. Variables not persisted do not appear in the table.

The SENSITIVE_VARIABLES_OBSERVER privilege is required to view the values of sensitive system variables in this table.

For information about persisted system variables, see Section 7.1.9.3, “Persisted System Variables”.

Suppose that mysqld-auto.cnf looks like this (slightly reformatted):

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{ "Version": 1, "mysql_server": { "max_connections": { "Value": "1000", "Metadata": { "Timestamp": 1.519921706e+15, "User": "root", "Host": "localhost" } }, "autocommit": { "Value": "ON", "Metadata": { "Timestamp": 1.519921707e+15, "User": "root", "Host": "localhost" } } } }

Then persisted_variables has these contents:

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mysql> SELECT * FROM performance_schema.persisted_variables; +-----------------+----------------+ | VARIABLE_NAME | VARIABLE_VALUE | +-----------------+----------------+ | autocommit | ON | | max_connections | 1000 | +-----------------+----------------+

The persisted_variables table has these columns:

  • VARIABLE_NAME

    The variable name listed in mysqld-auto.cnf.

  • VARIABLE_VALUE

    The value listed for the variable in mysqld-auto.cnf.

persisted_variables has these indexes:

  • Primary key on (VARIABLE_NAME)

TRUNCATE TABLE is not permitted for the persisted_variables table.