Performance Schema memory_summary_global_by_event_name Table

This table provides a global summary of memory usage events aggregated by event name, showing total memory allocation across the server.

The memory_summary_global_by_event_name table is available from MariaDB 10.5.2.

There are five memory summary tables in the Performance Schema that share a number of fields in common. These include:

• memory_summary_by_account_by_event_name

• memory_summary_by_host_by_event_name

• memory_summary_by_thread_by_event_name

• memory_summary_by_user_by_event_name

• memory_summary_global_by_event_name

The memory_summary_global_by_event_name table contains memory usage statistics aggregated by event and event.

The table contains the following columns:

Field	Type	Null	Default	Description
EVENT_NAME	varchar(128)	NO	NULL	Event name.
COUNT_ALLOC	bigint(20) unsigned	NO	NULL	Total number of allocations to memory.
COUNT_FREE	bigint(20) unsigned	NO	NULL	Total number of attempts to free the allocated memory.
SUM_NUMBER_OF_BYTES_ALLOC	bigint(20) unsigned	NO	NULL	Total number of bytes allocated.
SUM_NUMBER_OF_BYTES_FREE	bigint(20) unsigned	NO	NULL	Total number of bytes freed
LOW_COUNT_USED	bigint(20)	NO	NULL	Lowest number of allocated blocks (lowest value of CURRENT_COUNT_USED).
CURRENT_COUNT_USED	bigint(20)	NO	NULL	Currently allocated blocks that have not been freed (COUNT_ALLOC minus COUNT_FREE).
HIGH_COUNT_USED	bigint(20)	NO	NULL	Highest number of allocated blocks (highest value of CURRENT_COUNT_USED).
LOW_NUMBER_OF_BYTES_USED	bigint(20)	NO	NULL	Lowest number of bytes used.
CURRENT_NUMBER_OF_BYTES_USED	bigint(20)	NO	NULL	Current number of bytes used (total allocated minus total freed).
HIGH_NUMBER_OF_BYTES_USED	bigint(20)	NO	NULL	Highest number of bytes used.

Example

Seeing what memory was most often allocated for:

SELECT * FROM memory_summary_global_by_event_name 
  ORDER BY count_alloc DESC LIMIT 1\G
*************************** 1. row ***************************
                  EVENT_NAME: memory/sql/QUICK_RANGE_SELECT::alloc
                 COUNT_ALLOC: 147976
                  COUNT_FREE: 147976
   SUM_NUMBER_OF_BYTES_ALLOC: 600190656
    SUM_NUMBER_OF_BYTES_FREE: 600190656
              LOW_COUNT_USED: 0
          CURRENT_COUNT_USED: 0
             HIGH_COUNT_USED: 68
    LOW_NUMBER_OF_BYTES_USED: 0
CURRENT_NUMBER_OF_BYTES_USED: 0
   HIGH_NUMBER_OF_BYTES_USED: 275808

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