Bug #57320 Maximum width of row documented at 65,535 bytes is wrong
Submitted: 7 Oct 2010 16:47 Modified: 13 Jan 2011 15:51
Reporter: Kevin Benton Email Updates:
Status: Closed Impact on me:
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:5.1.47 OS:Any
Assigned to: Paul Dubois CPU Architecture:Any
Triage: Needs Triage: D3 (Medium)

[7 Oct 2010 16:47] Kevin Benton
In http://dev.mysql.com/doc/refman/5.1/en/column-count-limit.html, the MySQL documentation reports...

"Every table has a maximum row size of 65,535 bytes. This maximum applies to all storage engines, but a given engine might have additional constraints that result in a lower effective maximum row size."

This is not accurate because it is overly absolute. The statement does not consider BLOB/TEXT columns in the total picture. While it's true that in subsequent paragraphs, the writer negates the absolute statement but the damage has already been done.

How to repeat:
See Description

Suggested fix:
I propose this wording instead:

"Every table (regardless of storage engine) has a maximum row size of 65,535 bytes. BLOB and TEXT columns are counted at one to four plus eight bytes per column toward the row size limit because the contents of these columns are stored separately from the rest of the row. Storage engines may place additional constraints on this limit reducing the effective maximum row size."

It incorporates the third following paragraph into this one so that other paragraph becomes redundant.
[7 Oct 2010 16:50] Valeriy Kravchuk
Thank you for the documentation request.
[13 Jan 2011 15:51] Paul Dubois
Thank you for your bug report. This issue has been addressed in the documentation. The updated documentation will appear on our website shortly, and will be included in the next release of the relevant products.