These columns aggregate internal read locks. 

• COUNT_READ_NO_INSERT , SUM_TIMER_READ_NO_INSERT , MIN_TIMER_READ_NO_INSERT , AVG_TIMER_READ_NO_INSERT , MAX_TIMER_READ_NO_INSERT 

These columns aggregate internal read locks. 

• COUNT_READ_EXTERNAL , SUM_TIMER_READ_EXTERNAL , MIN_TIMER_READ_EXTERNAL , AVG_TIMER_READ_EXTERNAL , MAX_TIMER_READ_EXTERNAL 

These columns aggregate external read locks. 

• COUNT_WRITE_ALLOW_WRITE , SUM_TIMER_WRITE_ALLOW_WRITE , MIN_TIMER_WRITE_ALLOW_WRITE , AVG_TIMER_WRITE_ALLOW_WRITE , MAX_TIMER_WRITE_ALLOW_WRITE 

These columns aggregate internal write locks. 

• COUNT_WRITE_CONCURRENT_INSERT , SUM_TIMER_WRITE_CONCURRENT_INSERT , MIN_TIMER_WRITE_CONCURRENT_INSERT , AVG_TIMER_WRITE_CONCURRENT_INSERT , MAX_TIMER_WRITE_CONCURRENT_INSERT 

These columns aggregate internal write locks. 

• COUNT_WRITE_LOW_PRIORITY , SUM_TIMER_WRITE_LOW_PRIORITY , MIN_TIMER_WRITE_LOW_PRIORITY , AVG_TIMER_WRITE_LOW_PRIORITY , MAX_TIMER_WRITE_LOW_PRIORITY 

These columns aggregate internal write locks. 

• COUNT_WRITE_NORMAL , SUM_TIMER_WRITE_NORMAL , MIN_TIMER_WRITE_NORMAL , AVG_TIMER_WRITE_NORMAL , MAX_TIMER_WRITE_NORMAL 

These columns aggregate internal write locks. 

• COUNT_WRITE_EXTERNAL , SUM_TIMER_WRITE_EXTERNAL , MIN_TIMER_WRITE_EXTERNAL , AVG_TIMER_WRITE_EXTERNAL , MAX_TIMER_WRITE_EXTERNAL 

These columns aggregate external write locks. 

The table_lock_waits_summary_by_table  table has these indexes: 

•Unique index on ( OBJECT_TYPE , OBJECT_SCHEMA , OBJECT_NAME ) 

TRUNCATE TABLE  is permitted for table lock summary tables. It resets the summary columns to zero rather than removing rows. 

## 27.12.20.9 Socket Summary Tables 

These socket summary tables aggregate timer and byte count information for socket operations: 

• socket_summary_by_event_name : Aggregate timer and byte count statistics generated by the wait/io/socket/*  instruments for all socket I/O operations, per socket instrument. 

• socket_summary_by_instance : Aggregate timer and byte count statistics generated by the wait/ io/socket/*  instruments for all socket I/O operations, per socket instance. When a connection terminates, the row in socket_summary_by_instance  corresponding to it is deleted. 

