Here's what I would like to do: 1. hang a slave off my production master. 2. stop replication 3. adjust some data types and create some indexes on the slave (no data mods) 4. restart replication 5. once the slave has caught up, lock the db & swap slave & master
-the goal, obv. is to have no significant downtime while making some changes that will take time (200G table getting modified) -it should be possible, because the DDL changes I'm making have to do with shrinking data types & adding constraints - nothing that changes the actual values of data. -since GTID replication is row-based, I don't know if replication will choke trying to insert, for example, 11 digit ids into a 5 digit id column, even if the values are in range.