Bug #73768 Problem with indexes and change to UTF8mb4
Submitted: 29 Aug 2014 10:16 Modified: 29 Sep 2014 11:54
Reporter: John Woodford Email Updates:
Status: No Feedback Impact on me:
None 
Category:MySQL Server: DDL Severity:S2 (Serious)
Version:5.6.20 OS:Windows
Assigned to: CPU Architecture:Any
Tags: 1709, 767, 767 bytes, column, Error Code: 1709, INDEX, index column size, large, large, size, the maximum column size is 767 bytes, too

[29 Aug 2014 10:16] John Woodford
Description:
I have a database that has been working with no issues. Due to a requirement for 4-byte Unicode characters I have changed the character set from Latin to UTF8mb4. I now get the error message : Error Code 1709. Index Column is too large. The maximum column size is 767 bytes. Index column is BIGINT(20)

this link implies it is an issue in all MY SQL version 5.6.x :
http://database.ittoolbox.com/groups/technical-functional/sql-l/error-code-1709-the-maximu...

Is it really an issue for all versions?

When will there be a fix

How to repeat:
Change a database table to character set UTF8mb4 with an index with a size of BIGINT(20)

Suggested fix:
Ensure the column size can handle BIGINT(20) in utf8mb8
[29 Aug 2014 10:21] John Woodford
Using InnoDB as default storage engine
[29 Aug 2014 11:54] MySQL Verification Team
Thank you for the bug report. Please check http://dev.mysql.com/doc/refman/5.6/en/innodb-restrictions.html regarding " When the innodb_large_prefix configuration option is enabled, this length limit is raised to 3072 bytes, for InnoDB tables that use the DYNAMIC and COMPRESSED row formats.". Thanks.
[30 Sep 2014 1:00] Bugs System
No feedback was provided for this bug for over a month, so it is
being suspended automatically. If you are able to provide the
information that was originally requested, please do so and change
the status of the bug back to "Open".