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From:Daevid Vincent Date:August 6 2010 5:56pm
Subject:RE: Possible tricks to ALTER on huge tables?
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> -----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
think.

> 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.

Of course.

> 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.

Thread
Possible tricks to ALTER on huge tables?Daevid Vincent6 Aug
  • Re: Possible tricks to ALTER on huge tables?Buford Tannen6 Aug
  • Re: Possible tricks to ALTER on huge tables?Rob Wultsch6 Aug
    • RE: Possible tricks to ALTER on huge tables?Daevid Vincent6 Aug
  • Re: Possible tricks to ALTER on huge tables?Jigal van Hemert6 Aug
    • Re: Possible tricks to ALTER on huge tables?Andy Wallace6 Aug