MySQL8 Upgrade - Change Table Row Formats

[Mark Phillips]

I am currently prepping to upgrade from MySQL 5.7 to MySQL 8.

I am using RDS on AWS with a master server and read replicas. The read replicas use MySQL replication but read-only copies.

One of the issues I need to resolve prior to upgrade is that I have some tables on production databases with COMPACT row format which need updating to DYNAMIC.

I know I can do this with the following and have a script which will find and update all tables needed.

ALTER TABLE `tablename` ROW_FORMAT=DYNAMIC;

There are a large number of potentially large tables (millions of rows) that need updating.

What does this change actually do in the background? Is it safe to run this on a production server whilst it is in use?

I have done a test run on a restored copy of the server and this completes fine with no errors.