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From:ViSolve DB Team Date:April 17 2007 6:18am
Subject:Re: Max columns in a tabel in MyISAM storage engine
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Hi,

Might be column indexing have restriction over number of columns to be 
indexed,  but for number of columns, hope you can overrider with the 
variables
"avg_row_length" and "max_rows" during create/alter table.

The length/size of the table depends on the file system(maximum file size 
defined by the OS).  Try giving maximum value for avg_row_length.

Thanks
ViSolve DB Team
----- Original Message ----- 
From: "Fabian Köhler" <fab@stripped>
To: <mysql@stripped>
Sent: Tuesday, April 17, 2007 4:34 AM
Subject: Max columns in a tabel in MyISAM storage engine


> Hello,
>
> i have table with answers to questions. Every answer is a column in the 
> table. i.e.
>
> id|q1|q2|q3
> 1|answer1|answer2|answer5
> 2|answer3|answer4|asnwer6
>
> another option to save it would be sth like this:
>
> id|field|value
> 1|q1|answer1
> 1|q2|answer2
> 1|q3|answer5
> 2|q1|answer3
> ...
>
> The last one is not really useable when working with large amounts of 
> data, when you want to select i.e. 200 questions with answers it's 200*nof 
> answers queries to get them.
>
> The problem with the first solution is, that MyISAM storage engine is 
> limited to 2599 columns i think. So what's happening if i have more 
> answers than columns available?
>
> Does anybody have an idea? VIEWs or GROUP_CONCAT doesn't seem to be an 
> option, they are all to slow. What's the "right" way to store and select 
> such information?
>
> Thank you very much.
>
> regards,
>
> Fabian
>
> --
> Fabian Köhler      http://www.fabiankoehler.de
>
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Thread
Max columns in a tabel in MyISAM storage engineFabian Köhler17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineViSolve DB Team17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineMicah Stevens17 Apr
    • Re: Max columns in a tabel in MyISAM storage engineFabian Köhler17 Apr
      • Re: Max columns in a tabel in MyISAM storage engineMicah Stevens17 Apr
    • Re: Max columns in a tabel in MyISAM storage engineFabian Köhler17 Apr
    • Re: Max columns in a tabel in MyISAM storage engineFabian Köhler17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineStijn Verholen17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineMartijn Tonies17 Apr
  • RE: Max columns in a tabel in MyISAM storage engineJerry Schwartz17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineMartijn Tonies17 Apr
    • RE: Max columns in a tabel in MyISAM storage engineJerry Schwartz17 Apr
  • Re: Max columns in a tabel in MyISAM storage engineMartijn Tonies17 Apr
    • RE: Max columns in a tabel in MyISAM storage engineJerry Schwartz17 Apr
RE: Max columns in a tabel in MyISAM storage engineFabian Köhler17 Apr
  • RE: Max columns in a tabel in MyISAM storage engineJerry Schwartz17 Apr