• ./storage/innobase/srv/srv0mon.cc からコメント抜粋
• Number of delete-marked rows purged
• Number of times purge was invoked
• Number of undo log pages handled by the purge
• Number of purges on updates of existing records and
updates on delete marked record with externally stored
• Number of times buffer flush list flush is called
• Total pages scanned as part of LRU search
Maximum number of nested waits.
Some waits, such as:
are implemented by calling code in a storage engine,
that can cause nested waits (file io, mutex, ...)
Because of partitioned tables, a table io event (on the whole table)
can contain a nested table io event (on a partition).
Because of additional debug instrumentation,
waiting on what looks like a "mutex" (safe_mutex, innodb sync0sync, ...)
can cause nested waits to be recorded.
For example, a wait on innodb mutexes can lead to:
The max depth of the event stack must be sufficient
for these low level details to be visible.
sxlock is 何？
• https://dev.mysql.com/doc/refman/5.7/en/glossary.html#glos_rw_lock よ
• An sx-lock provides write access to a common resource
while permitting inconsistent reads by other threads. sx-
locks were introduced in MySQL 5.7 to optimize
concurrency and improve scalability for read-write workloads.