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Help on "Table Column-Count and Row-Size Limits"
Posted by: Arthur Smith
Date: August 02, 2012 03:07AM

Hello everyone,

I read this doc : http://dev.mysql.com/doc/refman/5.6/en/column-count-limit.html
Unfortunately the explanations aren't detailed enough for me.

I've to create a table with ~2500 fields.
I know that looks like a very bad idea, but I've to do it, and given that the limitation is 4096 columns per table it should be possible. I've tried to respect the maximum row size limitation of 65,535 bytes but it didn't work... let's do some maths :

I've 65k bytes and want to create 2500 fields, so 65000/2500= 26 bytes per field. I soustract 2bytes to store in a variable-length columns (varchar), and considering we are using utf 8 who uses 3bytes per char : 24/3 = 8, so I thought that varchar(8) will do the work. Not the case! I even try varchar(6) in case of a maths'mistake, but I still have the "too many fields" error !

If anyone can help me I would thankful,

Regards,

PS : I tried to use BLOB but it didn't work too, even blob(1). I don't know how to calculate with blob so I haven't try to go further.

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Help on "Table Column-Count and Row-Size Limits"
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August 02, 2012 03:07AM


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