Performance Schema Summary Tables •An external lock corresponds to a lock in the storage engine layer. This is currently implemented by a call to  handler::external_lock() . In event rows, these locks are distinguished by the  OPERATION column, which has one of these values: The  table_lock_waits_summary_by_table  table has these grouping columns to indicate how the table aggregates events:  OBJECT_TYPE ,  OBJECT_SCHEMA , and  OBJECT_NAME . These columns have the same meaning as in the  events_waits_current  table. They identify the table to which the row applies. table_lock_waits_summary_by_table  has the following summary columns containing aggregated values. As indicated in the column descriptions, some columns are more general and have values that are the same as the sum of the values of more fine-grained columns. For example, columns that aggregate all locks hold the sum of the corresponding columns that aggregate read and write locks. In this way, aggregations at higher levels are available directly without the need for user-defined views that sum lower- level columns. These columns aggregate all lock operations. They are the same as the sum of the corresponding xxx _READ  and  xxx _WRITE  columns. These columns aggregate all read-lock operations. They are the same as the sum of the corresponding xxx _READ_NORMAL ,  xxx _READ_WITH_SHARED_LOCKS ,  xxx _READ_HIGH_PRIORITY , and xxx _READ_NO_INSERT  columns. These columns aggregate all write-lock operations. They are the same as the sum of the corresponding xxx _WRITE_ALLOW_WRITE ,  xxx _WRITE_CONCURRENT_INSERT ,  xxx _WRITE_LOW_PRIORITY , and xxx _WRITE_NORMAL  columns. These columns aggregate internal read locks. These columns aggregate internal read locks. • COUNT_READ_HIGH_PRIORITY ,  SUM_TIMER_READ_HIGH_PRIORITY , MIN_TIMER_READ_HIGH_PRIORITY ,  AVG_TIMER_READ_HIGH_PRIORITY , MAX_TIMER_READ_HIGH_PRIORITY • COUNT_READ_NORMAL ,  SUM_TIMER_READ_NORMAL ,  MIN_TIMER_READ_NORMAL , AVG_TIMER_READ_NORMAL ,  MAX_TIMER_READ_NORMAL • COUNT_WRITE ,  SUM_TIMER_WRITE ,  MIN_TIMER_WRITE ,  AVG_TIMER_WRITE ,  MAX_TIMER_WRITE • COUNT_READ_WITH_SHARED_LOCKS ,  SUM_TIMER_READ_WITH_SHARED_LOCKS , MIN_TIMER_READ_WITH_SHARED_LOCKS ,  AVG_TIMER_READ_WITH_SHARED_LOCKS , MAX_TIMER_READ_WITH_SHARED_LOCKS • COUNT_READ ,  SUM_TIMER_READ ,  MIN_TIMER_READ ,  AVG_TIMER_READ ,  MAX_TIMER_READ • COUNT_STAR ,  SUM_TIMER_WAIT ,  MIN_TIMER_WAIT ,  AVG_TIMER_WAIT ,  MAX_TIMER_WAIT 5067 read normal read with shared locks read high priority read no insert write allow write write concurrent insert write delayed write low priority write normal read external write external