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)