Bug #92652 Documentation on row size limits has an error in an example
Submitted: 3 Oct 2018 8:32 Modified: 9 Oct 2018 7:06
Reporter: Sumeeti Lalwani Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server: Documentation Severity:S3 (Non-critical)
Version:8.0 OS:Any
Assigned to: CPU Architecture:Any
Tags: documentation, rowsize

[3 Oct 2018 8:32] Sumeeti Lalwani
Description:
The documentation on row size limits for version 8.0 gives 2 examples for  maximum row size for an InnoDB explaining that it is slightly less than half a page. The 2 examples that follow say:
1. "Row size is slightly less than 8KB for the default 16KB InnoDB page size."
2. "For 64KB pages, the maximum row size is slightly less than 16KB"

The second example should say "... it is slightly less than 32 KB"

How to repeat:
Visit this link https://dev.mysql.com/doc/refman/8.0/en/column-count-limit.html#row-size-limits and check out the row size limits section.

Suggested fix:
The second example should say "... it is slightly less than 32 KB"
[3 Oct 2018 8:35] Sumeeti Lalwani
Exists in documentation for 5.7 too, most likely introduced in that version as the example is not present for 5.6 and 5.5
[9 Oct 2018 7:06] MySQL Verification Team
Hello Sumeeti,

Thank you for the report.
I checked internally with the Innodb Dev and confirmed that this is by design and expected behavior(due to b-tree restrictions) which is even explicitly commented in code.

/* The maximum allowed record size is half a B-tree
               page(16k for 64k page size).  No additional sparse
               page directory entry will be generated for the first
               few user records. */

Marking this as !bg.

regards,
Umesh