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From:Johan De Meersman Date:November 11 2009 9:42pm
Subject:Re: storage difference in VARCHAR(size)?
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Aware of that, but char brings you certain performance benefits that
are good to know about if you need every last drop of juice :-)

On 11/11/09, Martijn Tonies <m.tonies@stripped> wrote:
>
>
>> Your mail suggests that you *are* seeing a difference, though. What
>> are you seeing?
>
> What I was saying, is that VARCHAR takes up space "l" (= length)
> of the data plus 1 or 2 bytes to store the length, while CHAR takes
> up the full space of the -defined- column size.
>
> This is rather wasteful when storing CHAR data that doesn't take up
> the full available space (as this is padded with spaces up to the defined
> length) and is a storage engine "feature" ;-)
>
> With regards,
>
> Martijn Tonies
> Upscene Productions
> http://www.upscene.com
>
> Download Database Workbench for Oracle, MS SQL Server, Sybase SQL
> Anywhere, MySQL, InterBase, NexusDB and Firebird!
>
> Database questions? Check the forum:
> http://www.databasedevelopmentforum.com
>
>
>> On 11/11/09, Martijn Tonies <m.tonies@stripped> wrote:
>>>>You have stumbled across the secret.  No, there is no difference at
>>>>all as the calculations suggested here confirm.
>>>>
>>>>http://dev.mysql.com/doc/refman/5.1/en/storage-requirements.html
>>>
>>> Note: as you can see in the above, CHAR data DOES take up room for it's
>>> full size, stupidly enough.
>>>
>>> On Tue, Nov 10, 2009 at 6:37 PM, Waynn Lue <waynnlue@stripped> wrote:
>>>> Hey all,
>>>>
>>>> I was building a table for storing email addresses today and ran into an
>>>> issue that I couldn't find an answer for using Google. If I declare the
>>>> column as a VARCHAR (this is an InnoDB table), does it matter what size
>>>> I
>>>> declare it as if it's between 1 and 255? I know there's an extra byte of
>>>> storage once it goes above 255 because of the length, but is there a
>>>> storage
>>>> difference between VARCHAR(100) and VARCHAR(255)? Obviously there's a
>>>> functional difference in what gets cut off when I try to store into that
>>>> table, but is that the only difference?
>>>
>>> With regards,
>>>
>>> Martijn Tonies
>>> Upscene Productions
>>> http://www.upscene.com
>>>
>>> Download Database Workbench for Oracle, MS SQL Server, Sybase SQL
>>> Anywhere, MySQL, InterBase, NexusDB and Firebird!
>>>
>>> Database questions? Check the forum:
>>> http://www.databasedevelopmentforum.com
>>>
>>>
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>>>
>
>
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Thread
storage difference in VARCHAR(size)?Waynn Lue11 Nov
  • Re: storage difference in VARCHAR(size)?Michael Dykman11 Nov
  • Re: storage difference in VARCHAR(size)?Martijn Tonies11 Nov
    • Re: storage difference in VARCHAR(size)?Johan De Meersman11 Nov
      • Re: storage difference in VARCHAR(size)?Waynn Lue11 Nov
  • Re: storage difference in VARCHAR(size)?Martijn Tonies11 Nov
    • Re: storage difference in VARCHAR(size)?Johan De Meersman11 Nov