The value of the
system variable affects the information available from the
tables described here. For details, see the description of
that variable in Section 5.1.5, “Server System Variables”.
The Performance Schema makes status variable information available in the tables described in Section 25.11.14, “Performance Schema Status Variable Tables”. It also makes aggregated status variable information available in summary tables, described here. Each status variable summary table has one or more grouping columns to indicate how the table aggregates status values:
VARIABLE_NAMEcolumns to summarize status variables by account.
VARIABLE_NAMEcolumns to summarize status variables by the host from which clients connected.
VARIABLE_NAMEcolumns to summarize status variables by client user name.
Each status variable summary table has this summary column containing aggregated values:
The aggregated status variable value for active and terminated sessions.
The meaning of “account” in these tables is
similar to its meaning in the MySQL grant tables in the
mysql system database, in the sense that
the term refers to a combination of user and host values. They
differ in that, for grant tables, the host part of an account
can be a pattern, whereas for Performance Schema tables, the
host value is always a specific nonpattern host name.
Account status is collected when sessions terminate. The session status counters are added to the global status counters and the corresponding account status counters. If account statistics are not collected, the session status is added to host and user status, if host and user status are collected.
Account, host, and user statistics are not collected if the
system variables, respectively, are set to 0.
The Performance Schema supports
TABLE for status variable summary tables as follows;
in all cases, status for active sessions is unaffected:
adds the session status from all active sessions to the global
status variables, resets the status of all active sessions,
and resets account, host, and user status values aggregated
from disconnected sessions.