From: Johan De Meersman
Date: June 14 2011 7:04pm
Subject: Re: Data missing after field optimization
List-Archive: http://lists.mysql.com/mysql/225254
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Heeh. That's not a random blog post, that's the official manual :-p

If it's in there, it's pretty much trustworthy; and I've learned something new :-) So apparently there's a dedicated "NULL" bit to columns... Yes, then there would be a small performance benefit.

I stand corrected. Still, as you've noticed, don't change the design of an existing application without thoroughly testing the consequences :-p


----- Original Message -----
> From: sono-io@stripped
> To: mysql@stripped
> Sent: Tuesday, 14 June, 2011 7:34:04 PM
> Subject: Re: Data missing after field optimization
> 
> It took me awhile, but I just found it again, in case anyone is
> interested:
> 
> http://dev.mysql.com/doc/refman/5.0/en/data-size.html
> 
> 
> 7.8.1. Make Your Data as Small as Possible
> 
> Declare columns to be NOT NULL if possible.  It makes everything
> faster and you save one bit per column. If you really need NULL in
> your application, you should definitely use it.  Just avoid having
> it on all columns by default.
> 
> Marc

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