PERFORMANCE_SCHEMA使用了多少内存？
在MySQL 5.6 通过运行“SHOW ENGINE PERFORMANCE_SCHEMA STATUS”并检查输出的最后一行(name = performance_schema.memory ),可以在运行时查看PERFORMANCE _ SCHEMA的内存消耗
<code >(Sun Sep 17 19:11:45 2023)[root@GreatSQL][(none)]>SHOW ENGINE PERFORMANCE_SCHEMA STATUS;
在MySQL 5.7上，您可以查询performance_schema本身来确定它使用了多少内存，例如:
<code >(Sun Sep 17 19:08:50 2023)[root@GreatSQL][(none)]>
SELECT SUM(CURRENT_NUMBER_OF_BYTES_USED)/1024/1024 SIZE_MB FROM performance_schema.memory_summary_global_by_event_name WHERE `EVENT_NAME` like 'memory/performance_schema%';
请参见内存核算表的手册页说明 http://dev.mysql.com/doc/refman/5.7/en/memory-summary-tables.html
