29.4.10 确定检测的内容
It is always possible to determine what instruments the Performance Schema includes by checking the setup_instruments
table. For example, to see what file-related events are instrumented for the InnoDB
storage engine, use this query:
mysql> SELECT NAME, ENABLED, TIMED
FROM performance_schema.setup_instruments
WHERE NAME LIKE 'wait/io/file/innodb/%';
+-------------------------------------------------+---------+-------+
| NAME | ENABLED | TIMED |
+-------------------------------------------------+---------+-------+
| wait/io/file/innodb/innodb_tablespace_open_file | YES | YES |
| wait/io/file/innodb/innodb_data_file | YES | YES |
| wait/io/file/innodb/innodb_log_file | YES | YES |
| wait/io/file/innodb/innodb_temp_file | YES | YES |
| wait/io/file/innodb/innodb_arch_file | YES | YES |
| wait/io/file/innodb/innodb_clone_file | YES | YES |
+-------------------------------------------------+---------+-------+
An exhaustive description of precisely what is instrumented is not given in this documentation, for several reasons:
-
What is instrumented is the server code. Changes to this code occur often, which also affects the set of instruments.
-
It is not practical to list all the instruments because there are hundreds of them.
-
As described earlier, it is possible to find out by querying the
setup_instruments
table. This information is always up to date for your version of MySQL, also includes instrumentation for instrumented plugins you might have installed that are not part of the core server, and can be used by automated tools.