I have inherited a WP site (with WP5.1 and WooCommerce 2.6.14, LearnDash 2.5.4 and few other smaller plugins).

From screenshot you can see that it is a mix and match of MyISAM and InnoDB tables.

We are experiencing table locking related problems (which essentially slow site down and result in 503 errors).

Even on such a simple table as wp_options we seem to have up to 10seconds lock times. Also on wp_posts.

Is it safe to convert tables from MyISAM to InnoDB? (we think that avoiding MyISAM table-level locking and switching to InnoDB row-level locking may help solve our issues).

ps. MySQL version 5.6.36-82.1-log - Percona Server (GPL), Release 82.1, Revision 1a00d79 (SiteGround)

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  • Couldn't you take a backup, convert them over, then test the site to see if it still works? I don't see why it wouldn't be safe, what are you worried might happen? – Tom J Nowell May 17 '19 at 1:10
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    Well, the whole setup is flimsy and I do not have confidence about backup/restore mechanisms the hosting provider offers. So I have to tread lightly. attempt to create staging environment failed; support agent tried 'repairing tables' and brought down all site; restored from yesterdays backup; i tried making simple db-dump and source into new db - this process took 15 mins and only worked as of 2nd attempt... Also as there's myriad plugins and they do who knows what - there's no reliable way to 'test site if it still works' - as pages may work, but some cron plugin hook may be breaking... – Dimitry K May 17 '19 at 3:34
  • Additional information request. Post on pastebin.com and share the links. RAM size of your MySQL Host server Text results of: B) SHOW GLOBAL STATUS; after minimum 24 hours UPTIME C) SHOW GLOBAL VARIABLES; D) SHOW FULL PROCESSLIST; E) complete MySQLTuner.pl (perl) report AND Optional very helpful information, if available includes - htop OR top OR mytop for most active apps, ulimit -a for a linux/unix list of limits, iostat -xm 5 3 for IOPS by device and core/cpu count, df -h for a linux/unix free space list by device, for server workload tuning analysis. – Wilson Hauck Jun 2 '19 at 23:53
  • @DimitryK Ready to make some progress? Consider posting additional information requested on Jun 2, 2019, please. – Wilson Hauck Dec 28 '19 at 21:43

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