Re: Avg_row_length

[Keith C. Ivey]

On 15 Jan 2003, at 13:03, Stefan Hinz wrote:

> > I believe there is an extra byte for the 'null' flag; if you declare
> > this column to be NOT NULL, I'll bet the avg length will be 10.
> 
> nice bet, but you lose <g>:

In addition to the bitmap for which columns have null values (if 
there are any columns that can be null), there's a similar bitmap to 
show which columns have zero values (or the empty string, for string 
columns).  That normally saves space because no additional storage is 
used if the column is zero.

There's a formula to calculate the row length for dynamic MyISAM 
tables here:

   http://www.mysql.com/doc/en/Dynamic_format.html

-- 
Keith C. Ivey <keith@stripped>
Tobacco Documents Online
http://tobaccodocuments.org
Phone [phone]