Bug #83283 Unclear info about UTF-8

• Submitted: 6 Oct 2016 9:36
• Modified: 19 Oct 2016 16:19
• Reporter: Daniël van Eeden (OCA)
• Status: Closed
• Category: MySQL Cluster: Documentation
• Severity: S3 (Non-critical)
• Version: 7.5
• OS: Any
• Assigned to: Jon Stephens
• CPU Architecture: Any
• Tags: Unicode, UTF-8

[6 Oct 2016 9:36] Daniël van Eeden

Description:
Page: https://dev.mysql.com/doc/ndbapi/en/ndb-start-mysql-ndb-mapping.html

"The storage space required for a MySQL CHAR column is determined by the maximum number of characters and the column's character set. For most (but not all) character sets, each character takes one byte of storage. When using UTF-8, each character requires three bytes. You can find the number of bytes needed per character in a given character set by checking the Maxlen column in the output of SHOW CHARACTER SET."

UTF-8 (the standard) has characters up to 4 bytes. 
utf8 (the MySQL charset) has characters up to 3 bytes (up until 5.7/7.5, where utf8 is an alias for utf8mb3)
utf8mb4 (the MySQL charset) has support for all UTF-8 characters and needs up to 4-byte per character.

How to repeat:
Check docs and implementation

[6 Oct 2016 9:46] MySQL Verification Team

Hello Daniël,

Thank you for the report.

Thanks,
Umesh

[19 Oct 2016 16:19] Jon Stephens

Fixed in mysqldoc rev 49553. Closed.