MySQL Bugs: #80870: Optimize TC_LOG

Bug #80870	Optimize TC_LOG_MMAP
Submitted:	28 Mar 2016 18:07	Modified:	27 Dec 2017 14:30
Reporter:	George Lorch	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: Logging	Severity:	S4 (Feature request)
Version:	5.6, 5.7	OS:	Any
Assigned to:		CPU Architecture:	Any

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Description:
It seems TC_LOG_MMAP is not optimized nearly as well as TC_LOG_BIN.

How to repeat:
Enabling (but not necessarily using) a second transactional storage engine (such as TokuDB) and log_bin=OFF, the MySQL server will always use TC_LOG_MMAP.

We see much higher disk usage when TC_LOG_MMAP is in use (even for InnoDB only workloads) and PMP shows a lot of time spent in TC_LOG_MMAP::sync.

For more background info, see https://bugs.launchpad.net/percona-server/+bug/1550352

Hi!

Thank you for your report.

I have analysed the code and concluded that this is a fully valid feature request. Hence, it is verified as one.