> -----Original Message-----
> From: Rob Wultsch [mailto:wultsch@stripped]
> Sent: Thursday, August 05, 2010 6:05 PM
> To: Daevid Vincent
> Cc: MySQL List
> Subject: Re: Possible tricks to ALTER on huge tables?
> Having significant amount of overhead for unused columns will without
> doubt harm performance significantly for certain operations.
I don't see this as "significant overhead". A few "null" columns that are
dormant are not going to impact performance in any measurable way I don't
> Altering .frm files should is always be tried on a non-prod box before
> even considering using it on prod.
Thanks Capt'n Obvious. ;-p
Isn't that the case for ANY and ALL DB operations?
> There are some well known use cases
> (adding enums values, enlarging varchar columns) where altering a .frm
> is useful, but it should always be considered very dangerous.
> You could of course consider using PostgreSQL which would only need a
> very brief exclusive lock for adding a default null column...
...an interesting thought.