It appears that this issue is no longer being worked on, so we are closing it for housekeeping purposes. If you believe the issue still exists, please open a new ticket after confirming it's present in the latest release.

OK, so altering a table comment in MyRocks really can't be done inline due to TTL functionality.  If a user was changing the TTL specification, the table needs to be rebuilt/copied with the new TTL stored within each key.  We can't (easily) check the table or index comments for the TTL specification at the point that we have to make the decision on whether or not an inplace alter can be performed.  So this is one that will probably have to be sent upstream to consider and will likely never get corrected.  There is a similar issue with column families and index comments where we just can't determine 1) what the users intentions are w.r.t. a comment change; and 2) if the comment change would force the move of and index from one column family to another at the point where we need to decide if we can support inplace alter for the operation.

This is not specific to 8.0. Fix for 5.7 and 8.0 will be somewhat different due to changes in 8.0 user interface from . Not likely to be a large amount of time. Maybe 'Fix if time' but this is really a minor thing, when one considers other holes in ALTER (like INPLACE not supported in 8.0).

8.0 Triage meeting would like your recommendation on this one.