Wordpress and Buddypress Min/Max Lengths of Username, Password, Display Name, URL and BP Registration text fields

WP_Users Table

UserName is maximum of 60 characters long, min 1 character, technically albeit not good. To prevent collisions, the bigger min size the better. 

1	ID	bigint(20)
2	user_login	varchar(60)	utf8mb4_unicode_ci
3	user_pass	varchar(255)	utf8mb4_unicode_ci
4	user_nicename	varchar(50)	utf8mb4_unicode_ci
5	user_email	varchar(100)	utf8mb4_unicode_ci
6	user_url	varchar(100)	utf8mb4_unicode_ci
7	user_registered	datetime
8	user_activation_key	varchar(255)	utf8mb4_unicode_ci
9	user_status	int(11)
10	display_name	varchar(250)	utf8mb4_unicode_ci

A Buddypress field can be a maximum length of 4,294,967,295 or 4GB (2³² − 1) characters.

WP_BP_xprofile_data Table 

This table contains all text fields entered data from BuddyPress Edit/Registration Form.

1	id	bigint(20)
2	field_id	bigint(20)
3	user_id	bigint(20)
4	value	longtext	utf8mb4_unicode_520_ci

For example, a edit/registration form to collect City, will be housed in field 4, value, longtext value = "New York".

A full list MYSQL datatypes is defined here -> https://dev.mysql.com/doc/refman/5.7/en/string-type-overview.html

• LONGTEXT 4,294,967,295 bytes ~4GB
• MEDIUMTEXT 16,777,215 bytes ~16MB
• TEXT 65,535 bytes ~64kb
• TINYTEXT 256 bytes