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From:Keith C. Ivey Date:January 15 2003 3:39pm
Subject:Re: Avg_row_length
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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
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Thread
Avg_row_lengthStefan Hinz14 Jan
  • RE: Avg_row_lengthJennifer Goodie15 Jan
  • Re: Avg_row_lengthSteve Edberg15 Jan
  • Re: Avg_row_lengthDan Nelson15 Jan
  • Re: Avg_row_lengthStefan Hinz15 Jan
    • Re: Avg_row_lengthSteve Edberg15 Jan
    • Re: Avg_row_lengthKeith C. Ivey15 Jan
      • Re: Avg_row_lengthStefan Hinz16 Jan
        • Re: Avg_row_lengthKeith C. Ivey16 Jan
          • Re: Avg_row_lengthStefan Hinz16 Jan
            • Re: Avg_row_lengthSergei Golubchik16 Jan
            • Re: Avg_row_lengthZak Greant16 Jan
          • Re: Avg_row_lengthgerald_clark16 Jan
          • Re: Avg_row_lengthStefan Hinz16 Jan
            • Re: Avg_row_lengthSergei Golubchik17 Jan
            • Re: Avg_row_lengthRoger Baklund17 Jan
          • Re: Avg_row_lengthgerald_clark17 Jan
          • Re: Avg_row_lengthStefan Hinz17 Jan
  • Re: Avg_row_lengthStefan Hinz15 Jan
  • Re: Avg_row_lengthStefan Hinz15 Jan