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buffer busy waits

A buffer busy wait occurs if multiple processes want to access a buffer in the buffer cache concurrently.
The type of buffer that causes the wait can be queried with v$waitstat. v$waitstat lists the waits per buffer type for buffer busy waits only. Therefore, the following SQL statement always returns 0
select
  (select total_waits from v$system_event
  where event='buffer busy waits')
-  /* minus */
  (select sum(count) from v$waitstat)
from
  dual;

Type of block waited for

Buffer busy waits is one of the events that Oracle records while it is running.