Re: innodb_undo_directory

[Jim Hetland]

I thought I had subscribed to this thread, but evidently not, so I thought there had been no replies. Thank you Rick James, but your reply isn't really an answer, and borders on condescending; if I hadn't identified the disk contention associated with the undo logs as a problem, I wouldn't be trying so hard to make this work. Though it does seems I'm the only one so foolish.

Anyway, I did demonstrate that innodb_undo_directory does work on a new instance, and there isn't any obvious way to apply it later (as the helpful linked article also states), other than, in my case, copying terabytes of data, probably with the database halted, since FLUSH TABLES ... FOR EXPORT doesn't work either. (sorry, I really don't mean to sound so churlish)

Anyway there's a good workaround for innodb_undo_directory: place the system tablespace on a different physical drive from the per-file tablespaces. The undo logs are in the system tablespace; little else is; heavy contention solved.